FNA: Astragalus

Key to Species of Group 1 and Other Groups

1. Leaflets usually 5 or 7, decurrent, blade apex spinulose; Great Plains westward.	A. kentrophyta
1. Leaflets (0 or)1 or 3–39(–43), often not decurrent, blade apex not spinulose (except A. detritalis, sometimes A. spatulatus); widespread.	→ 2
2. Plants with malpighian hairs; leaflets usually 3, rarely 1 or 5, stipules (3–)4–18 mm, connate-sheathing, hyaline; legumes 3–10 mm, unilocular.	→ 3
3. Plants acaulescent and tuft-, cushion-, or mound-forming; flowers 12.3–29 mm; calyces cylindric.	→ 4
4. Flowers 16–29 mm, banner not differentiated into blade and claw, petals glabrous, rarely banner puberulent adaxially.	A. gilviflorus
4. Flowers 12.3–17.5 mm, banner differentiated into blade and claw, with shoulderlike projections at middle, petals glabrous or villous abaxially.	→ 5
5. Petals glabrous abaxially; flowering May; Sweetwater County, sw Wyoming.	A. proimanthus
5. Petals villous abaxially; flowering June–August; ne Colorado, Kansas, Montana, w Nebraska, North Dakota, South Dakota, Wyoming e of Continental Divide.	A. hyalinus
3. Plants caulescent and mat- or cushion-forming, or acaulescent or subacaulescent, and pulvinate and mat- or cushion-forming; flowers 5–16.7 mm; calyces usually campanulate, rarely subcylindric.	→ 6
6. Flowers 5–8 mm; calyces 2.4–4.2 mm.	→ 7
7. Plants cushion- or mat-forming; stems prostrate; stipules densely pilose abaxially; racemes (2 or) 3–5-flowered; flowers 5–6.2(–8) mm.	A. sericoleucus
7. Plants pulvinate, cushion-forming; stems not prostrate (obscured by stipules); stipules glabrous or glabrate abaxially (margins ciliate); racemes 2- or 3-flowered; flowers (5.8–)6.6–8 mm.	A. aretioides
6. Flowers 8.2–16.7 mm; calyces 4.5–7.1 mm.	→ 8
8. Flowers 8.2–11.5 mm; keel petals 4.4–7.2 mm; calyx tubes 1.8–3.5(–3.8) mm; stipules (at least proximalmost) pilose abaxially.	A. tridactylicus
8. Flowers (9.5–)10.5–16.7 mm; keel petals 7.5–10.5 mm; calyx tubes 3.6–5.1 mm; stipules glabrous abaxially.	A. barrii
2. Plants with malpighian or basifixed hairs; leaflets usually 5–39(–43), rarely 0, 1, or 3 (seldom 3, with malpighian hairs); stipules 1–13(–20) mm, distinct, or sometimes connate-sheathing, foliose, herbaceous, papery, membranous, submembranous, scarious, or semileathery, not hyaline; legumes (0.9–)1–45(–75) mm, unilocular, bilocular, or semibilocular.	→ 9
9. Leaflets 1, blades ovate, orbiculate, or cordate.	A. asclepiadoides
9. Leaflets (0 or)1 or 3–39(–43), if 1, then blades much longer than broad, usually spatulate.	→ 10
10. Plants perennial, from rhizomelike or stoloniferous caudex; leaflets (5 or)7–13(or 15), pinnately veined; stipules of most proximal, leafless nodes connate, apex obtuse, distal stipules foliose; legumes simultaneously pendulous, stipitate, inflated, and unilocular.	→ 11
11. Plants 5–30(–36) cm; calyces campanulate to subcylindric, tubes 6.3–8 mm.	A. umbellatus
11. Plants 25–90(–100) cm; calyces campanulate, tubes (4.3–)4.9–5.8 mm.	A. americanus
10. Plants usually perennial, rarely annual, from a taproot or caudex; leaflets (0 or)1 or 3–39(–43), pinnate venation sometimes absent or inconspicuous; most proximal stipules distinct or connate, if connate, apex emarginate or bidentate, distal stipules rarely foliose; legumes not simultaneously pendulous, stipitate, inflated, and unilocular.	→ 12
12. Calyces obliquely ovoid, accrescent and inflated; legumes deciduous within accrescent calyces; Upper San Juan Valley, sw Colorado, adjacent New Mexico.	A. oocalycis
12. Calyces usually campanulate or cylindric, not accrescent and inflated; legumes not deciduous within calyces; widespread.	→ 13
13. Plants usually with malpighian hairs	Group 2
13. Plants with basifixed hairs.	→ 14
14. Plants annual, short-lived perennials, or flowering first year	Group 3
14. Plants perennial (sometimes short-lived).	→ 15
15. Terminal leaflet of all or only distal leaves decurrent and not jointed to rachis	Group 4
15. Terminal leaflet jointed to rachis.	→ 16
16. Stipules connate-sheathing proximally or throughout.	→ 17
17. Legumes stipitate, or sessile and gynophores (1–)1.3–11 mm	Group 5
17. Legumes sessile or subsessile, stipe 0–1.7 mm, gynophore absent (except to 2 mm in A. tennesseensis)	Group 6
16. Stipules distinct throughout.	→ 18
18. Legumes stipitate, or sessile and gynophores 0.3–5(–12) mm	Group 7
18. Legumes sessile or subsessile, gynophores absent or to 1 mm.	→ 19
19. Plants acaulescent or subcaulescent and stem shorter than leaves or inflorescence	Group 8
19. Plants caulescent, main stem longer than longest leaves or inflorescences	Group 9

Key to Species of Group 2

1. Plants short-lived perennial or flowering as annual; wc to se Arizona.	A. arizonicus
1. Plants usually long-lived perennial (except A. amphioxys, A. lotiflorus, and A. piscator); widespread.	→ 2
2. Leaves reduced to phyllodia proximally or throughout, leaflet blades, when present, oblanceolate, linear, linear-oblanceolate, or spatulate.	→ 3
3. Leaves 1–13(–17) cm; racemes loosely 7–23-flowered, in bud resembling grass spikelets; plants of sandstone hogbacks and cuestas in pinyon-juniper and mixed desert shrub communities; Uintah Basin, Utah.	A. chloödes
3. Leaves 0.8–10 cm; racemes usually densely 1–11-flowered, in bud not resembling grass spikelets; plants of pinyon-juniper, sagebrush, and mountain brush communities, hilltops, exposed ridges, summits and gullied slopes of bluffs; Kansas to Utah, north to Saskatchewan and Alberta.	→ 4
4. Flowers 5.2–9.5 mm, keel petals 3.7–6 mm; legumes 4–8.5(–13) mm; fruiting calyces not prominently veined.	→ 5
5. Legumes laterally compressed; Kansas to Utah, north to Saskatchewan and Alberta.	A. spatulatus
5. Legumes 3-sided compressed; Sublette County, Wyoming.	A. drabelliformis
4. Flowers 10.6–20 mm, keel petals 7–12.8(–13.4) mm; legumes 6–13(–15) mm and fruiting calyces prominently veined, or 15–38 mm and fruiting calyces not prominently veined.	→ 6
6. Leaves reduced to phyllodia; legumes 6–13(–15) × 2–5 mm, narrowly ovoid-ellipsoid to lanceoloid-ellipsoid; Carbon, Fremont, and Natrona counties, Wyoming.	A. simplicifolius
6. Leaves 3–7-foliolate distally; legumes 15–38 × 2–3.5 mm, linear-oblong; Moffat and Rio Blanco counties, Colorado, Duchesne and Uintah counties, Utah.	A. detritalis
2. Leaves pinnate throughout, or reduced to phyllodia distally, leaflet blades filiform, oblong, elliptic, oblanceolate, obovate, linear, oblong-obovate, ovate, linear-oblong, suborbiculate-obcordate, oval, subrhombic, or rhombic.	→ 7
7. Leaves reduced to phyllodia distally or pinnate; terminal leaflet of distal leaves often not jointed to rachis and sometimes decurrent; plants caulescent.	→ 8
8. Peduncles and racemes together longer than stems, much surpassing subtending leaves; plants selenophytes; n Arizona, se Utah.	A. moencoppensis
8. Peduncles and racemes together usually not or not much surpassing subtending leaves; plants not selenophytes; North Dakota to Idaho south to Kansas and Arizona.	→ 9
9. Plants slender, not clump-forming, from rhizomelike, subterranean caudex; stems sprawling; stipules connate distally, subscarious or herbaceous; legumes sessile, subsessile, or stipitate, bladdery-inflated, purple-mottled, ellipsoid; e Montana, sw North Dakota south to Arizona, New Mexico, and Oklahoma, west to s Idaho, Utah.	A. ceramicus
9. Plants stout (coarse), clump-forming, from subterranean caudex, not rhizomelike; stems erect or ascending; stipules distinct, papery or foliaceous; legumes sessile, laterally compressed, not purple-mottled, narrowly oblong; e footslope of San Rafael Swell, Emery, Garfield, and Wayne counties, Utah.	A. woodruffii
7. Leaves usually pinnate, sometimes unifoliolate; terminal leaflets jointed to rachis; plants caulescent or acaulescent.	→ 10
10. Plants from rhizomes, not clump-forming; legumes erect or narrowly ascending, oblong or cylindroid.	→ 11
11. Plants (10–)15–120(–160) cm, internodes not short or flexuous; plants of moist, though often summer-dry, communities; widespread in United States east of Sierra-Cascade axis and Canada.	A. canadensis
11. Plants 6–20(–25) cm, internodes relatively short and strongly flexuous; plants of arid, sandy knolls or swales and talus; sc Wyoming to ne, sc Montana.	A. oreganus
10. Plants from superficial caudex, mat-, cushion-, or clump-forming; legumes declined-pendulous, ascending, spreading, erect, or reflexed, linear, ovoid, oblong, oblanceoloid, lanceoloid, or lanceoloid-ellipsoid.	→ 12
12. Legumes erect, ascending, reflexed, or declined, bilocular; plants caulescent.	→ 13
13. Flowers 4.5–6(–7) mm; plants villosulous, villous, or pilose, hairs basifixed, sub-basifixed, or malpighian; sc Idaho to e Oregon, and c, sc Washington.	A. caricinus
13. Flowers 8.7–19.5 mm; plants strigulose, hairs malpighian; Ontario to Alaska, south to Kansas, Arizona, and Oregon.	→ 14
14. Flowers ascending; raceme axis (1.5–)2.5–10 cm in fruit; wc to se Arizona.	A. arizonicus
14. Flowers declined or ascending; raceme axis (0.6–)3–20 cm in fruit; Ontario to Alaska, south to Iowa, New Mexico, and Washington.	→ 15
15. Flowers declined; legumes deflexed; pedicels 3.2–6.5 mm; calyces 3.6–4.7 mm.	A. falcatus
15. Flowers ascending; legumes erect; pedicels to 0.8 mm; calyces 5.6 to 10.5 mm.	A. laxmannii
12. Legumes mostly ascending or spreading, sometimes erect, rarely declined or pendulous, unilocular (except A. anisus, A. calycosus, and A. terminalis); plants acaulescent, subacaulescent, or caulescent.	→ 16
16. Plants acaulescent; wing petals with deeply cleft apex; peduncles scapelike; legumes bilocular.	A. calycosus
16. Plants acaulescent or caulescent; wing petals with entire or obscurely emarginate apex; peduncles not scapelike; legumes mostly unilocular (bilocular in A. anisus and A. terminalis).	→ 17
17. Stipules mostly connate-sheathing, at least proximally.	→ 18
18. Stems prostrate; plants mat- or cushion-forming, caulescent.	→ 19
19. Racemes 3–30-flowered; corollas greenish to ochroleucous or purple; leaflets (5–)9–17(or 19); habitats various, usually not sandstone escarpments.	A. humistratus
19. Racemes 1–4-flowered; corollas pink-purple; leaflets 7–11(–17); sandstone escarpments.	A. sesquiflorus
18. Stems erect, ascending, decumbent, or prostrate; plants sometimes tuft- or mat-forming, caulescent or acaulescent.	→ 20
20. Legumes obovoid to ellipsoid, stipitate (stipes 0.5–1 mm); plants slender, delicate; New Mexico.	→ 21
21. Racemes 5–10(–14)-flowered; plants of escarpments; Sandoval County, New Mexico.	A. knightii
21. Racemes (1 or) 2–4-flowered; plants of disturbed or compacted soils; Capitan Mountains, Lincoln County, New Mexico.	A. kerrii
20. Legumes ovoid, lanceoloid-ellipsoid, oblong, or ellipsoid, sessile (except A. albulus); plants robust, not or rarely slender or delicate; widespread.	→ 22
22. Plants caulescent or shortly so, not selenophytes; legumes declined-pendulous, linear, linear-oblong, linear-ellipsoid, or oblanceoloid, laterally compressed; plants usually of mountains or steppes; Alberta and British Columbia south to Washington, e Nevada, Utah, Wyoming.	A. miser
22. Plants caulescent, selenophytes; legumes erect, ascending, declined, or pendulous, oblong, oblong-ellipsoid, or lanceoloid-ellipsoid, dorsiventrally or laterally compressed; plants usually of fine-textured desert substrates; Wyoming west to Nevada, south to Texas and Arizona.	→ 23
23. Peduncles (0.7–)1–3(–4) cm, racemes slightly surpassing subtending leaves; Coconino County, Arizona.	A. sophoroides
23. Peduncles 1–23 cm, racemes shorter than or surpassing subtending leaves; Wyoming west to Nevada, south to Texas and Arizona.	→ 24
24. Peduncles (3–)5–23 cm, surpassing subtending leaves; plants flowering April–July (or September); wc, s Wyoming, south through w Colorado, northeast to sw Utah, s Nevada, n Arizona, nw New Mexico.	A. flavus
24. Peduncles 1–4(–5.5) cm, much shorter than subtending leaves; plants flowering July–October; ne Arizona, sw Colorado, n New Mexico, w Texas.	A. albulus
17. Stipules mostly distinct throughout (sometimes connate-sheathing proximally in A. amphioxys, distinct proximally but connate distally in A. wittmannii).	→ 25
25. Plants acaulescent or subacaulescent, mat-, tuft-, or cushion-forming; flowers 3.7–18(–21) mm; leaves 0.3–9 cm; legumes 3–7.5 mm; rimrock at Grand Canyon and vicinity and Mogollon Rim, Arizona, sw Colorado, nw New Mexico.	→ 26
26. Plants tuft-forming, 6–25 cm; leaves (1.5–)2.5–9 cm; leaflets (7–)11–21(–25), blades (2–)3–12 mm; peduncles ± scapelike, (2.5–)3.5–15(–22) cm; racemes 17–26-flowered.	A. gilensis
26. Plants tuft-, mat-, or cushion-forming, 0.5–3(–3.2) cm; leaves 0.3–3(–8) cm; leaflets (3 or)5–11, blades 1–5(–12) mm; peduncles axillary or obsolete, 0.2–0.6 cm; racemes 1–3-flowered.	→ 27
27. Caudex branches with spinose-persistent leaf bases; legumes laterally compressed; extreme sw Colorado and adjacent nw New Mexico.	A. humillimus
27. Caudex branches with non-spinose, marcescent leaf bases; legumes subterete, laterally compressed, or obcompressed; Grand Canyon and vicinity, Arizona, c New Mexico.	→ 28
28. Racemes 1-flowered; pedicels obsolete; calyces cylindric; Colfax, Harding, and Mora counties, New Mexico.	A. wittmannii
28. Racemes (1 or) 2 (or 3)-flowered; pedicels 0.7–3.5 mm; calyces campanulate; Arizona, c New Mexico.	→ 29
29. Flowers 9–11.5 mm, keel petals 7.5–8.7 mm; legumes 5–7.5 mm, laterally compressed; seeds 8–10; c New Mexico.	A. siliceus
29. Flowers 3.7–8 mm, keel petals 3.7–5.7 mm; legumes 3-4.5(–4.8) mm, slightly flattened or basally compressed abaxially; seeds 4–6; Grand Canyon area, Arizona.	A. cremnophylax
25. Plants caulescent, subacaulescent, or acaulescent, usually loosely tuft-forming, or if somewhat mat-forming, then not with tiny leaves, legumes, and flowers; flowers (7–)8.5–28(–32) mm; leaves 1–17 cm; legumes (8–)9–40 mm; Manitoba to British Columbia, south to Missouri, Texas, and Arizona.	→ 30
30. Plants caulescent; stems erect, decumbent, or incurved-ascending, with 2–4 much-elongated internodes; peduncles 6–20 (–24) cm; corollas white except keel apex dark; flowers nodding; legumes erect.	A. terminalis
30. Plants subacaulescent to acaulescent, or short stemmed to caulescent (when short caulescent, then stems usually prostrate, A. lotiflorus sometimes erect); stems obsolete, reduced to crowns, prostrate, erect, ascending, or decumbent, internodes usually not elongated, often concealed by stipules; peduncles 0.4–15(–20) cm; corollas pink, purple, or white with or without dark keel apex; flowers erect to spreading; legumes ascending or spreading, or descending.	→ 31
31. Calyces shallowly campanulate, tubes 3.2–4.5 mm; flowers 8.5–14 mm.	A. lotiflorus
31. Calyces cylindric, campanulate, vase-shaped, or cylindro-campanulate, tubes (3.4–)4–14 mm; flowers (7–)10–32 mm.	→ 32
32. Leaflets (1 or)3 or 5.	→ 33
33. Leaflet blades 5–35(–47) mm; corollas pink-purple; caudex with thatch of persistent leaf bases.	A. musiniensis
33. Leaflet blades 5–25 mm; corollas ochroleucous, greenish white, purple, or pink-purple; caudex with or without thatch of persistent leaf bases.	→ 34
34. Corollas purple or pink-purple; plants of alluvium, often on terraces of ancient Pleistocene lakes, ne Nye County, Nevada, Millard County, Utah.	A. uncialis
34. Corollas ochroleucous or greenish white and keel tip purple; plants of igneous gravel, c Sevier County, Utah.	A. loanus
32. Leaflets mostly 5–21, seedlings and early leaves with fewer.	→ 35
35. Leaflets usually 5–11(or 13) (to 18 in A. cymboides).	→ 36
36. Legumes plumply ovoid and moderately obcompressed, hirsute (hairs 2–2.5 mm); corollas ochroleucous or greenish white, often faintly purplish-tinged; Garfield, Iron, Kane, Millard, Piute, and Wayne counties, Utah.	A. welshii
36. Legumes lanceoloid-ellipsoid or oblong to oblong-ellipsoid, laterally compressed or cylindroid becoming laterally compressed, strigose (hairs relatively short); corollas pink-purple or ochroleucous, sometimes suffused pink or purple, or lined purple; Colorado, Utah.	→ 37
37. Flowers 18–24 mm.	A. piscator
37. Flowers 15–18.5 mm.	A. cymboides
35. Leaflets of at least some leaves 11–21.	→ 38
38. Legumes densely shaggy-hirsute; flowers 21–25 mm; Washington and adjacent Iron counties, Utah.	A. concordius
38. Legumes usually strigulose or strigose, rarely glabrous; flowers 7–24(–28) mm; Manitoba west to Alberta, south to Texas and Arizona.	→ 39
39. Legumes obliquely globose, oblong-globose, or broadly obovoid, apex minutely cuspidate, not or scarcely beaked, bilocular (septum 3–6 mm wide); Gunnison County, Colorado.	A. anisus
39. Legumes obliquely ovoid or oblong, lanceoloid-ovoid, ellipsoid, or crescentic, apex distinctly beaked, unilocular or subunilocular; Manitoba west to Alberta, south to Texas and Arizona.	→ 40
40. Calyces 4.6–5.1 mm; flowers 7–8.3 mm, ochroleucous or purple-veined or -margined; legumes plumply ovoid or oblong-ellipsoid; Zuni Mountains, McKinley County, New Mexico.	A. accumbens
40. Calyces 5–14.2(–14.3) mm; flowers 9.5–27(–28) mm; legumes obliquely ovoid or oblong, lanceoloid-ovoid, lunately ellipsoid, ellipsoid, oblong-ellipsoid, or crescentic; Manitoba west to Alberta, south to Texas and Arizona.	→ 41
41. Legumes fleshy becoming alveolate-spongy (walls 1+ mm thick, exocarp and endocarp separated by thick, pulpy mesocarp).	→ 42
42. Legumes oblong-ovoid or ellipsoid (not markedly thicker near base); Colorado, Montana, Utah, Wyoming (not in or near Henry Mountains).	A. chamaeleuce
42. Legumes turgidly lanceoloid-ovoid (broader proximally); near Henry Mountains, w Garfield and w Wayne counties, Utah.	A. laccoliticus
41. Legumes leathery or fleshy becoming leathery, papery, or subligneous (walls much less than 1 mm thick).	→ 43
43. Legumes obliquely ovoid, lanceoloid-ovoid, or lunately ellipsoid, (8–)9–20(–22) mm; flowers 10–18.5 mm; corollas usually whitish, ochroleucous, or tinged purplish, rarely purple; c, n Arizona, c Utah.	→ 44
44. Flowers (14.5–)15–18.5 mm; calyces 6–10.5 mm; herbage usually silky-strigose to strigulose (hairs lustrous); Arizona into e Kane County, Utah.	A. castaneiformis
44. Flowers 10–15.5(–17.5) mm; calyces 5.5–8.9 mm; herbage strigulose (not especially lustrous); sc Utah.	A. consobrinus
43. Legumes crescentic, subsymmetrically or obliquely oblong, oblong-ellipsoid, or ellipsoid, (11–)15–40 mm; flowers 9.5–27(–28) mm; corollas usually pinkish purple, rarely white; sc Canada to sc and sw United States.	→ 45
45. Legumes readily deciduous.	A. amphioxys
45. Legumes persistent or tardily deciduous.	A. missouriensis

Key to Species of Group 3

1. Legumes (2–)2.3–4.2 mm; ovules 2.	→ 2
2. Flowers ascending becoming spreading or declined; racemes elongating in fruit; legumes strongly obcompressed; s Oregon southward.	A. gambelianus
2. Flowers erect or ascending; racemes not elongating in fruit; legumes somewhat laterally compressed; San Joaquin Valley and s Coast ranges, California, s Nevada, s Arizona, southward.	A. didymocarpus
1. Legumes (0.9–)5–40 mm; ovules (3 or)4–38.	→ 3
3. Legumes spreading (in oblong or globose heads), coiled through 0.7–1.3 spiral into 6–8 mm diam. ring; Massachusetts.	A. contortuplicatus
3. Legumes erect, ascending, spreading, reflexed, horizontal, declined, or pendulous (not in oblong or globose heads), straight, decurved, or incurved, not coiled more than 0.5 spiral; w and se United States.	→ 4
4. Legumes hirsute, hairs spreading-ascending, to 1.2–1.8 mm, lustrous; Alabama, Florida, Georgia, and South Carolina.	A. villosus
4. Legumes strigose, strigulose, villosulous, hirsutulous, hirsute, or glabrous, when hirsute, then hairs less than 1 mm (except A. sabulonum hairs to 2.2 mm), not lustrous; w United States to Montana, Kansas, and Louisiana.	→ 5
5. Legumes reflexed, 5.5–9 mm, sessile with gynophores 0.1–0.5 mm; Texas.	A. reflexus
5. Legumes erect, ascending, spreading, reflexed, horizontal, declined, or pendulous, (2.4–)5–50(–57) mm, sessile, stipitate, or with gynophores 0.4–2.5 mm; w United States including Texas.	→ 6
6. Legumes sessile, oblong to lanceoloid-oblong and without gynophores, or peltiform and with gynophores; Texas.	→ 7
7. Legumes reflexed, peltiform, gynophores 1.5–2.3 mm; seeds 4; s Texas.	A. brazoensis
7. Legumes erect, oblong to lanceoloid-oblong, sessile; seeds 5–9; c, e Texas.	A. wrightii
6. Legumes sessile or stipitate, with or without gynophores, globose to linear or crescentic or oblong; w United States including Texas.	→ 8
8. Legumes ascending to erect, oblong-ellipsoid, stipitate (stipes 3–3.5 mm); selenophytes; San Juan County, Utah.	A. cutleri
8. Legumes globose to linear or crescentic or oblong-ellipsoid, sessile or stipitate, sometimes with gynophores; not selenophytes; if legumes ascending to erect, oblong-ellipsoid and stipitate then not in San Juan County, Utah.	→ 9
9. Legumes obovoid to oblong-ellipsoid, 10–18 mm; flowers 4–6(–7) mm; banners abruptly recurved through 90°; Arizona, sw Colorado, New Mexico, se Utah.	A. brandegeei
9. Legumes globose to linear or crescentic or oblong-ellipsoid; flowers (3.3–)3.7–12.5(–13.2) mm; banners recurved through 90(–125)°, when flowers 4–7 mm, then banner curvature reflexed to 45°; w United States.	→ 10
10. Legumes semiellipsoid or lunately ellipsoid, slightly inflated, scarcely bladdery; racemes (3 or)4–9-flowered; flowers (3.3–)3.5–6.5 mm; Yuma County, Arizona, Imperial, Riverside, and San Diego counties, California.	A. aridus
10. Legumes globose to linear or crescentic, bladdery or not; racemes 1–35-flowered; flowers (3.7–)5–18.5 mm; not simultaneously with legumes semiellipsoid or lunately ellipsoid, racemes with fewer than 9 flowers, and flowers less than 6.5 mm; sw United States north to Washington, Montana, east to Kansas, southeast to Louisiana.	→ 11
11. Legumes unilocular to subunilocular or semibilocular, generally obliquely ovoid to globose, inflated and often bladdery (± inflated in A. sparsiflorus), papery or papery-membranous.	→ 12
12. Legumes unilocular, subunilocular, or semibilocular, septum at least partial at base, often narrow.	→ 13
13. Leaflets (5 or)7 or 9; racemes 2–8-flowered; legumes bladdery-inflated, 6–12 mm wide; Larrea deserts in s Nevada, nw Arizona.	A. geyeri
13. Leaflets 9–19; racemes (3–)7–15-flowered; legumes somewhat inflated, almost bladdery, 3–9 mm wide; e Oregon (formerly sc Washington).	A. diaphanus
12. Legumes unilocular, septum absent, even at base.	→ 14
14. Racemes mostly (3–)5–35-flowered.	→ 15
15. Racemes and legumes in subglobose or oblong heads; plants of alkaline flats and seeps.	A. hornii
15. Racemes and legumes not in subglobose or oblong heads; plants not halophytic.	→ 16
16. Plants annual or biennial, slender; John Day Valley and lower Columbia River, e Oregon (formerly sc Washington).	A. diaphanus
16. Plants annual, biennial, or short-lived perennial, ± coarse; Texas and California north to Colorado and Washington.	→ 17
17. Banner recurved through 90°; seeds 21–32; sandy desert shrublands.	A. fucatus
17. Banner recurved through 50°; seeds (10–)13–21; habitats various.	→ 18
18. Legumes with strongly developed beak, clearly differentiated from body; Arizona to w Texas.	A. allochrous
18. Legumes with short and obscure beak, not well differentiated from body; e Mojave Desert, California, to w Texas.	A. wootonii
14. Racemes (1 or)2–15-flowered.	→ 19
19. Legumes villosulous, villous, or hirsute, hairs spreading, curly.	→ 20
20. Plants short-lived perennials; legumes straight or slightly incurved, 13–21 × 7–11 mm; seeds 20–28.	A. pardalinus
20. Plants annuals or biennials; legumes lunately incurved or hooked, 9–17(–20) × (4–)5–8(–11) mm; seeds 10–19.	A. sabulonum
19. Legumes strigulose, hairs appressed, straight.	→ 21
21. Legumes ± inflated, not bladdery; e slope of Colorado Rocky Mountains.	A. sparsiflorus
21. Legumes mostly strongly inflated, bladdery; Montana, Wyoming, Utah west to Washington and California.	→ 22
22. Leaflets 7–11; legumes subsymmetric, 11–17 mm, seed-bearing flange 3–3.5 mm wide; seeds 28–30; lower Little Colorado River, Coconino County, Arizona.	A. endopterus
22. Leaflets (3–)7–19(or 21), when 11+, then either flowers 6.3+ mm or purple or legumes strongly asymmetric and incurved or less than 11 mm wide; legumes sometimes similar in size and outline, usually smaller, seed-bearing flange to 2.5 mm wide; seeds (6 or)7–24; Montana to Washington, south to California, Arizona, and Utah.	→ 23
23. Leaflet blades mostly ovate or obovate-obcordate; legumes translucent.	A. diaphanus
23. Leaflet blades mostly oblong-elliptic to linear; legumes translucent or not.	→ 24
24. Corollas usually whitish, purple in c Nevada; legumes green or suffused purple, becoming stramineous; n United States to s Nevada and adjacent Arizona, to Mono County, California.	A. geyeri
24. Corollas pinkish purple or reddish purple; legumes pale green becoming stramineous, sometimes purple-suffused or -dotted; Panamint Mountains and Mojave Desert, California, to adjacent Arizona.	→ 25
25. Flowers 7.8–10.4 mm; leaflets 7–13; legumes with seed-bearing flange 1–2.5 mm wide; seeds 19–24; Panamint Mountains and e Mojave Desert, south to Chuckwalla Mountains, Riverside County, California.	A. nutans
25. Flowers 5.5–7.4 mm; leaflets (9 or) 11–19 (or 21); legumes with seed-bearing flange 0.2–1.5 mm wide; seeds 7–12(–14); Colorado Desert, California, north to Chuckwalla Mountains, w Arizona southward.	A. insularis
11. Legumes bilocular, generally oblong to linear or crescentic and not inflated, if broader than oblong or inflated, then valves fleshy becoming stiffly papery, leathery, or subligneous.	→ 26
26. Plants annual and perennial in same populations.	→ 27
27. Leaflet blade abaxially strigulose, adaxially glabrous or sometimes medially glabrate; legumes ascending; Arizona, New Mexico.	A. nothoxys
27. Leaflet blade silvery-strigulose (appearing frosted); legumes declined, pendulous, or spreading; California, Nevada.	→ 28
28. Legumes 13–18 × 2.8–3.5 mm, thinly papery; seeds 8–11; east end of San Bernardino Mountains, California.	A. albens
28. Legumes (13–)15–28(–32) × 3.5–8.5 mm, fleshy becoming leathery or subligneous; seeds 20–30; Mojave Desert, California, s Nevada.	A. mohavensis
26. Plants annual (winter or spring).	→ 29
29. Legumes dehiscent while still attached to plants.	→ 30
30. Flowers (12–)13–18.5 mm; keel petals 9.5–13 mm; legumes 3.5–6(–6.5) mm wide, stipes (0.8–)1–2.6(–3) mm; styles puberulent proximal to stigmas; seeds 8–12(–14); Oklahoma, Texas.	A. lindheimeri
30. Flowers 3.7–13(–13.2) mm; keel petals 3.7–7.8(–9.3) mm; legumes (1.6–)2.1–4.1 mm wide, stipes or gynophores 0–0.9 mm; styles glabrous; seeds 10–26; w United States east to Louisiana.	→ 31
31. Flowers (5.2–)8.3–12(–13.2) mm; keel petals (4.5–)6–7.8(–9) mm, apex narrowly acute-triangular (beaklike); leaflet blade apex retuse or emarginate; legumes straight or slightly incurved, (17–)20–37 mm, glabrous; seeds 20–26.	A. leptocarpus
31. Flowers 3.7–13 mm; keel petals 3.7–6.8(–9.3) mm, apex acute-triangular to obtusely rounded, beaklike or not; leaflet blade apex emarginate, retuse, truncate, rounded, obtuse or acute; legumes nearly straight, gently incurved, or incurved through 0.2–0.5 spiral, (7–)10–26 mm, strigulose, villosulous, hirsutulous, or glabrous; seeds 10–22.	→ 32
32. Legumes ascending, spreading, or declined, strigulose, villosulous, or glabrous, hairs straight; w United States east to Alabama.	A. nuttallianus
32. Legumes declined, hirsutulous, hairs curved; Inyo County, California, Clark and Nye counties, Nevada, and sw Washington County, Utah.	A. nyensis
29. Legumes dehiscent after detaching from plant.	→ 33
33. Apex of keel bluntly deltate or narrowly triangular and ± acute; Texas to California, north to Utah.	→ 34
34. Legumes glabrous and apex of keel bluntly deltate; nw, se Arizona, New Mexico, Texas, sc Utah.	A. emoryanus
34. Legumes usually strigulose, sometimes glabrous, when glabrous, apex of keel acutely triangular; Arizona, s Nevada, se California.	A. acutirostris
33. Apex of keel round or deltate; California North Coast Ranges, Great Valley, South Coast Ranges, along coast from Monterey to San Diego.	→ 35
35. Seeds borne in proximal 1/2 of legume; legume ovoid, ovoid-oblong, or fusiform, 5.5–10 mm, densely silvery-strigulose, apex abruptly contacted into a (glabrescent) spinelike beak; North Coast Ranges, Mendocino and Lake to Marin counties.	A. breweri
35. Seeds borne near middle of legume; legume narrowly crescentic, linear, linear-oblong, or lanceoloid-oblong, (6–)10–50(–57) mm, strigulose, villosulous, or glabrous, usually not spinose-beaked; widespread in California, including North Coast Ranges.	→ 36
36. Keel petals 7.4–9.1 mm, wings 6.7–9 mm, keel petals subequal to or to 1.6 mm longer than wings; legumes crescentic and linear (base and apex acuminate), gynophore slender, 1.4–2.5 mm; Napa and Sonoma counties.	A. claranus
36. Keel petals 3.4–8.1 mm, wings 4.5–10.4 mm, keel petals shorter than wings; legumes linear-oblong, lanceoloid-oblong, narrowly crescentic, or narrowly linear, stipes (0–)2.7–5 mm; North Coast Ranges, South Coast Ranges, Great Valley, and along coast from Monterey to San Diego counties.	→ 37
37. Legumes (15–)18–57 mm, if less than 21 mm, then base cuneate-tapered or substipitate; North and South Coast ranges.	A. rattanii
37. Legumes 6–20 mm (to 50 mm in A. tener var. ferrisiae), base rounded; Great Valley and along coast from Monterey to San Diego.	→ 38
38. Racemes 2–12-flowered, subcapitate, axis 0.2–0.8 cm in fruit, (when more than 5 mm, then 7–12-flowered); legumes green becoming stramineous; plants of low alkaline meadows and depressions along coast, bluffs or dunes; elevation 0–60 m.	A. tener
38. Racemes 2–5(–7)-flowered, axis (0.4–)0.7–2 cm in fruit; legumes mottled or suffused with purple, resupinate; plants of moist, open sites, foothill oak woodlands, treeless summits; elevation 40–1200 m.	A. pauperculus

Key to Species of Group 4

1. Legumes stipitate, stipes 2.5–15 mm (as short as 1 mm in A. yoderwilliamsii).	→ 2
2. Stipules distinct throughout.	→ 3
3. Legumes strongly laterally compressed, faces ± flattened.	→ 4
4. Corollas pink-purple; sw Wyoming to c, se Utah, ne Arizona, nw New Mexico, sw Colorado.	A. coltonii
4. Corollas pale lemon yellow; sc Colorado, nc New Mexico.	A. ripleyi
3. Legumes mostly dorsiventrally compressed, sometimes laterally compressed or subterete, faces convex or not.	→ 5
5. Flowers spreading-declined; corollas ochroleucous or nearly white, banner 13.5–24 mm; stipes 3–15 mm; Colorado and New Mexico west to Arizona and Nevada.	→ 6
6. Leaflets (1 or)3–9 (or 11), blades 0.5–4 mm wide; plants often on low-quality substrates; n Arizona, w, s Colorado, e Nevada, n New Mexico, s, w Utah, barely extending into Uinta Basin.	A. lonchocarpus
6. Leaflets (1 or)3–7, blades 2–9(–13) mm wide; plants mainly on Cretaceous Mowry Shale and Tertiary Duchesne River and closely associated formations; Moffat County, Colorado, and Uinta Basin, Utah.	A. hamiltonii
5. Flowers ascending or declined; corollas pink-purple, banner 8–14 mm; stipes 2.5–6 mm; Utah.	→ 7
7. Plants 15–51 cm; leaves mostly pinnate; calyces (3.5–)3.8–7 mm; flowers (9–)10–15 mm; axis of raceme 1.5–28 cm in fruit; e Garfield, San Juan, and Wayne counties.	A. nidularius
7. Plants 40–70 cm; leaves pinnate proximally, reduced to rachis with terminal leaflet distally; calyces 2.5–4.6 mm; flowers 8–10.5 mm; axis of raceme 5–40(–42) cm in fruit; Garfield and Wayne counties.	A. harrisonii
2. Stipules connate-sheathing proximally, connate or distinct distally.	→ 8
8. Legumes bladdery-inflated, unilocular, papery-membranous (translucent); n Idaho, Malheur County, Oregon, Asotin County, Washington.	A. cusickii
8. Legumes 3-sided and bilocular, or dorsiventrally or laterally compressed and unilocular, thin or fleshy becoming papery or leathery, or subligneous; British Columbia to Montana, south to Arizona.	→ 9
9. Legumes sharply 3-sided, bilocular.	→ 10
10. Plants caulescent and slender, 10–30 cm; stems spreading to ascending and diffuse; leaflet blades 1–11 mm; legumes 9–16 × 3–4.5 mm; elevation 600–900(–1000) m; Snake River and tributaries in sw Idaho and e Malheur County, Oregon.	A. mulfordiae
10. Plants short-stemmed and diminutive (densely tuft-forming), 1–3(–7) cm; stems erect or ascending; leaflet blades 1–3 mm; legumes 4–7 × 2–3 mm; elevation 1500–2200 m; sw Owyhee County, Idaho, ec Humboldt County, Nevada.	A. yoderwilliamsii
9. Legumes dorsiventrally or laterally compressed, unilocular.	→ 11
11. Plants clump-forming, from elongated subterranean caudex with deeply set taproot; plants of sandstone soils; se Utah.	A. nidularius
11. Plants clump-forming or not, from shallow subterranean or superficial caudex; plants often of seleniferous, basaltic, or pumice soils, not sandstone; California, Colorado.	→ 12
12. Leaflets of proximal leaves (5–)7–15, blades linear-oblong or oblanceolate, reduced distally, most distal leaves unifoliolate and filiform; legumes strongly laterally compressed, body linear-ellipsoid, 7–12-times longer than wide; corollas white; Grand County, Colorado.	A. osterhoutii
12. Leaflets 5–21(–23), reduced distally, blades filiform to oblong-elliptic or oblanceolate; legumes laterally or dorsiventrally compressed or terete, body linear-oblong, linear-lanceolate, obliquely oblong, or clavate-ellipsoid, 4–9 times longer than wide; corollas pinkish red or greenish white, drying ochroleucous; California.	→ 13
13. Leaflets 5–11; calyces 3.5–5 mm, lobes 0.6–1 mm; legumes strongly laterally compressed, 3–4 mm wide; seeds 13–17; n California.	A. inversus
13. Leaflets (11 or)13–21(or 23); calyces 8.1–10.1 mm, lobes 1.8–3.3 mm; legumes not compressed or somewhat obcompressed becoming dorsiventrally compressed, 5–8.5(–9) mm wide; s California.	A. bicristatus
1. Legumes sessile or subsessile, stipes or gynophores 0–1.7(–2) mm.	→ 14
14. Flowers (10–)14–30 mm (sometimes as small as 12 mm in A. woodruffii and 10 mm in A. nelsonianus); calyces cylindric (obliquely ovoid and accrescent in A. oocalycis), tubes (3.8–)4–10.2(–14) mm.	→ 15
15. Stipules at the most proximal nodes distinct (often obscurely connate in A. woodruffii).	→ 16
16. Legumes erect.	→ 17
17. Leaflet blades silvery-silky throughout; legumes narrowly oblong, 14–24 × 2.5–4.8 mm, laterally compressed, stiffly papery, strigulose; plants of sandy footslopes of the San Rafael Swell and environs, Utah.	A. woodruffii
17. Leaflet blades often silvery-canescent, more densely so adaxially; legumes obliquely ovoid or plumply oblong, 15–31 × 5–12 mm, subterete, fleshy becoming woody, glabrous; Death Valley, California, Lahontan Basin and environs, Nevada.	A. serenoi
16. Legumes pendulous.	→ 18
18. Leaflets 9–23, blades linear, narrowly oblong, or elliptic, 1–33 × 0.3–3.2 mm (when linear, less than 20 mm); legumes sharply 4-sided compressed, 20–40 × 6–10 mm, strongly incurved or coiled; ne Arizona, sw Idaho, se, w, n Nevada, se Oregon, sw Utah.	A. tetrapterus
18. Leaflets 3–7(or 9), blades linear, 10–50 × 0.5–1.5 mm; legumes strongly obcompressed, (25–)30–45 × (11–)13–17(–23) mm, ± straight or obscurely sigmoid-arcuate; nc, nw Nevada.	A. pterocarpus
15. Stipules at the most proximal nodes connate.	→ 19
19. Calyces accrescent, hirsute; legumes 6–7.5 mm, deciduous within calyces; Upper San Juan Valley, sw Colorado, adjacent New Mexico.	A. oocalycis
19. Calyces not accrescent, strigose, strigulose, or glabrate; legumes 9–35 mm, well exserted beyond persistent calyces; Manitoba to Alberta south to Kansas, Arizona, and Oregon.	→ 20
20. Corollas white, ochroleucous, or cream; leaves pinnate throughout, not reduced distally; e of Continental Divide except at 1900–2200 m in Montana, sw Wyoming, adjacent Utah.	→ 21
21. Stems ascending or erect; legumes erect or ascending; Carbon County, Montana, se to Carbon County, Wyoming.	A. grayi
21. Stems decumbent, ascending, or erect; legumes declined or deflexed; Manitoba to Alberta south to Kansas and Utah, including Wyoming.	→ 22
22. Flowers (16–)21–24(–27) mm; calyx tubes 2.8–4.3 mm wide; leaflet blades involute, linear, filiform, or linear-oblanceolate, rigid; Alberta east to Manitoba, southward to Colorado and Kansas.	A. pectinatus
22. Flowers 24–30 mm; calyx tubes 4.5–6.2 mm wide; leaflet blades flat (margins elevated), linear-oblong, not rigid; sw Wyoming to Moffat County, Colorado, and Daggett County, Utah.	A. nelsonianus
20. Corollas usually pink-purple with white or whitish wing tips, white with pink-purple keel tips, greenish yellow, rarely white throughout; leaves pinnate proximally and unifoliolate distally or all unifoliolate, sometimes reduced to naked rachis (phyllodia); plants of intermountain region, w Colorado to n Arizona, nw Nevada, se Oregon, and s Idaho.	→ 23
23. Legumes erect; n Arizona, wc Colorado, nw Utah to Idaho, Nevada, Oregon.	→ 24
24. Corollas pink-purple with white wing tips, or greenish yellow, or whitish; racemes 7–35-flowered; n Arizona, Utah to Idaho, Nevada, Oregon.	A. toanus
24. Corollas white with pink-purple keel tips; racemes 3–10-flowered; Delta and Montrose counties, Colorado.	A. linifolius
23. Legumes declined or deflexed; wc, nw Colorado, c, ne Utah.	→ 25
25. Corollas pale pink-purple, wing tips often paler or sometimes white; legumes oblong-ellipsoid, 12–25 × 5–7.5 mm, glabrous, terminal cusps 2.5–4 mm; San Rafael Swell, Utah, along lower Dolores River, wc Colorado.	A. rafaelensis
25. Corollas usually pink-purple with white wing tips, rarely white throughout; legumes narrowly oblong, (15–)20–35 × 4.4–6(–7) mm, strigose or glabrate, terminal cusps 0.5–1 mm; Uinta County, Utah.	A. saurinus
14. Flowers 4.3–13.5(–15.5) mm; calyces campanulate (except shortly cylindric in A. episcopus), tubes 1.2–5.6(–6) mm.	→ 26
26. Flowers 4.3–6.1 mm; calyx tubes 1.2–1.8 mm; legumes 9–12 × 2.5–3 mm, strongly laterally compressed; McKinley County, New Mexico.	A. cliffordii
26. Flowers 5–13.5(–15.5) mm; calyx tubes (1.5–)1.8–5.6(–6) mm; legumes 5–35(–40) × (1.2–)1.9–9(–11) mm, 3-sided compressed, dorsiventrally compressed, obcompressed, bladdery-inflated, or laterally compressed, sometimes strongly so; w North America.	→ 27
27. Flowers 5–7.5 mm; calyx tubes 1.8–2.1 mm; legumes 5–8 × 1.9–3(–3.3) mm; Crook, Deschutes, and n Klamath counties, Oregon.	A. peckii
27. Flowers (5–)6.3–15.5 mm; calyx tubes (1.5–)2.3–5.6(–6) mm; legumes (5.5–)10–35(–40) × (1.2–)2–9 mm; w North America.	→ 28
28. Legumes linear-oblong, linear-oblanceoloid, or narrowly ellipsoid, 10–22 × 2.3–4.3 mm, subsessile or stipitate, stipes 0–2 mm (stipes concealed within calyces when present), dorsiventrally compressed; se California, sw Idaho, Nevada, e Oregon.	A. atratus
28. Legumes linear to subglobose, 5.5–40 × (1.2–)2–11 mm, sessile, subsessile, or shortly stipitate, stipes 0–1.7 mm, laterally compressed, sometimes strongly so, obcompressed, or bladdery-inflated; w North America.	→ 29
29. Plants rushlike; leaflet blades mostly linear or reduced to a rachis (rarely elliptic or oblong).	→ 30
30. Legumes dorsiventrally compressed in proximal 1/2, laterally compressed distally.	A. duchesnensis
30. Legumes laterally compressed throughout, sometimes strongly so.	→ 31
31. Corollas ochroleucous; banners recurved through 100–130°.	A. xiphoides
31. Corollas pale pink or whitish to pink-purple or tinged purplish or pinkish; banners recurved through 40–45°.	→ 32
32. Calyces shortly cylindric, suffused with purple or pale, white-strigose, tubes 3.4–5.2(–6) × 1.9–2.9(–3.4) mm; seeds 16–26.	A. episcopus
32. Calyces campanulate, not suffused with purple, black-strigose, tubes 2.8–4.2 × 2.2–2.6 mm; seeds 8–14.	A. lancearius
29. Plants mostly not rushlike; leaflet blades of at least some leaves broader than linear.	→ 33
33. Plants selenophytes, 1–5 cm (dwarf) and densely clump-, cushion-, or tuft-forming, or 9–60 cm and clump-forming, from superficial or slightly subterranean caudex.	→ 34
34. Plants densely clump-, cushion-, or tuft-forming; leaves 1–4 cm; peduncles 0.5–3.5 cm; racemes 3–7-flowered; legumes spreading, bladdery-inflated, 10–17 × 7–11 mm; plants not scented.	A. jejunus
34. Plants clump-forming; leaves 4–17 cm; peduncles 4–25 cm; racemes 6–34-flowered; legumes ascending-spreading, obcompressed (not bladdery), 5.5–8 × 2.3–3.4 mm; plants garliclike scented.	A. moencoppensis
33. Plants not selenophytes, (1–)10–60(–80) cm, clump-forming or not, from subterranean or superficial caudex.	→ 35
35. Legumes ellipsoid to oblong, 9–15 mm; ne Arizona, w Colorado, nw New Mexico, e Utah (n to Uintah County).	A. wingatanus
35. Legumes linear, linear-oblong, linear-ellipsoid, oblanceoloid, or narrowly oblong, 10–50(–53) mm; w North America.	→ 36
36. Caudex superficial, with leafy spurs on caudex or base of stems forming basal tufts; Alberta, British Columbia, southward to Arizona and New Mexico, eastward to South Dakota.	A. miser
36. Caudex subterranean or superficial, without leafy spurs on caudex or base of stems (without basal tufts); Montana to Colorado, west to Idaho and Arizona.	→ 37
37. Plants from deep subterranean caudex; leaves often nearly bladeless and rushlike; leaflet blades, when present, 5–30 × 0.5–4 mm; legumes 13–50(–53) × 2.3–5 mm; plants usually of dry or woodland habitats.	A. convallarius
37. Plants from shallow subterranean or superficial caudex (and a stout, tuberous taproot); leaves often expanded into flat, grasslike blades; leaflet blades 4–47(–67) × 1–5 mm; legumes 10–17 × 2.7–4 mm; plants usually of moist meadows and stream banks, in moist saline meadows and swales.	A. diversifolius

Key to Species of Group 5

1. Plants caulescent, villous-hirsute or shaggy-villous, hairs minutely dilated at base; flowers nodding; corollas whitish or ochroleucous; legumes narrowly oblong to oblanceoloid, obscurely 3-sided compressed, glabrous, bilocular.	A. drummondii
1. Plants subcaulescent to caulescent, mostly strigulose, villous to villosulous, or pilose; flowers nodding or not; corollas pink, purple, lavender, red, yellow, ochroleucous, cream, white, or greenish white; legumes, when oblong to lanceoloid, not bluntly 3-sided compressed, glabrous or pubescent, unilocular to bilocular.	→ 2
2. Legumes ovoid, leathery or stiffly papery, bilocular; corollas whitish tinged with violet; leaflet blades obovate-cuneate or suborbiculate, apex obtuse to emarginate; plants local in Rush and Skull valleys, Tooele County, Utah.	A. lentiginosus
2. Legumes, when ovoid, then cartilaginous, papery, papery-membranous, fleshy, or leathery, unilocular to bilocular; corollas pink, purple, lavender, red, yellow, ochroleucous, cream, white, or greenish white; leaflet blades filiform or narrowly elliptic to broadly obovate, apex acute to emarginate; widespread.	→ 3
3. Calyces obliquely ovoid, tubes accrescent, legumes enclosed, deciduous within accrescent calyx; upper San Juan Valley, sw Colorado, adjacent New Mexico.	A. oocalycis
3. Calyces usually campanulate or cylindric, when ovoid, tubes not accrescent, legumes not deciduous within calyx; widespread.	→ 4
4. Legumes obcompressed, bladdery-inflated, or terete, not laterally angled, unilocular.	→ 5
5. Legumes sessile on, and disjointing from, stipelike gynophore, 2.3–11 mm.	→ 6
6. Calyces 6–8.6 mm; leaflets 25–39; flowers 13–16 mm; gynophores 2.3–5.6(–6) mm; legumes bladdery-inflated, not laterally compressed, not bicarinate, 23–36 × 12–18(–20) mm; coastal or near coastal California, San Luis Obispo County south to Santa Barbara County, on San Miguel and Santa Rosa isles.	A. curtipes
6. Calyces (5.5–)8.7–10.3 mm; leaflets (11–)17–29(or 31); flowers 15.3–18(–19) mm; gynophores 3–11 mm; legumes bladdery-inflated and laterally compressed, bicarinate, (21–)25–45 × (6–)8–15.5 mm; South Coast Ranges, Stanislaus County, south to Santa Barbara, Kern, and San Luis Obispo counties, California.	A. oxyphysus
5. Legumes stipitate or, if sessile, then gynophore to 1 mm.	→ 7
7. Legumes erect, papery, stipes 7–19 mm; caudex subterranean; purple Triassic Chinle Formation in Kane and Washington counties, Utah, and Mohave County, Arizona.	→ 8
8. Stems prostrate-ascending; corollas ochroleucous, or pink-purple with white wing tips; e Washington and Kane counties, Utah, w of Cockscomb Segment of East Kaibab, and adjacent Mohave and Coconino counties, Arizona.	A. ampullarius
8. Stems erect-ascending from decumbent base; corollas ochroleucous; sc, sw Washington County, Utah.	A. ampullarioides
7. Legumes usually pendulous or declined, sometimes spreading or loosely ascending, cartilaginous or papery-membranous, stipes 1.5–12(–40) mm, or gynophores 0–1 mm; caudex subterranean or superficial; Alaska and w United States.	→ 9
9. Legumes sessile or articulate to short gynophore; caudex subterranean, rhizomatous; racemes 1–3(–6)-flowered; c, w Alaska.	A. polaris
9. Legumes subsessile or stipitate; caudex subterranean or superficial; racemes (3 or)4–45-flowered; Colorado and New Mexico west to Washington and California.	→ 10
10. Legumes cartilaginous becoming stiffly papery, somewhat fleshy, opaque; s Utah southward.	A. hallii
10. Legumes papery-membranous, translucent; sc New Mexico to California and Washington.	→ 11
11. Stipes 14–40 mm; c, sc, w California.	A. asymmetricus
11. Stipes 1.5–12 mm; New Mexico to California and Washington.	→ 12
12. Stipes 1.5–3 mm; legumes ovoid, often red-mottled; sc New Mexico.	A. castetteri
12. Stipes 2–12 mm; legumes ovoid, semiobovoid, or semiellipsoid, red- or purple-mottled or not; Idaho and Washington south to Nevada and California.	→ 13
13. Legumes ± obliquely obovoid, semiobovoid, or semiellipsoid, apex differentiated into broad, low-deltoid beak; wc, sw Idaho, e, se Oregon, sw Washington.	A. cusickii
13. Legumes subsymmetrically obovoid, apex broad, round, beak obsolete; s California to Washington, eastward to ne Nevada and c Idaho.	A. whitneyi
4. Legumes not inflated or, if swollen, then slightly bladdery or angled laterally or bluntly, unilocular or bilocular.	→ 14
14. Flowers nodding and retrorsely imbricate, (12.5–)14–23.5 mm; stipes (3.5–)4–22 mm.	→ 15
15. Corollas dull yellow; legumes fleshy becoming woody, unilocular, bicarinate by sutures; Sierra Nevada of California, Lake Tahoe n in Nevada.	A. gibbsii
15. Corollas white, ochroleucous, or pink-purple; legumes papery or fleshy becoming thinly leathery, unilocular or bilocular, when unilocular, legumes 3-sided compressed or dorsiventrally compressed, sometimes abaxially bisulcate; widespread.	→ 16
16. Plants odorless; caudex subterranean; legumes 3-sided, abaxially sulcate, bilocular.	A. scopulorum
16. Plants with garliclike odor; caudex superficial; legumes dorsiventrally compressed or 3-sided, faces flat or bisulcate, unilocular.	→ 17
17. Legumes with contrasting faces, adaxial face convexly rounded, abaxial face with suture forming a prominent ridge flanked by depressed grooves; corollas often pink-purple, sometimes white or ochroleucous; c Nevada eastward.	A. bisulcatus
17. Legumes sharply 3-sided, faces of subequal width and nearly flat; corollas usually white or ochroleucous, rarely suffused with purple or purple-veined; sw Wyoming, ne Utah to Texas north to Saskatchewan.	A. racemosus
14. Flowers erect to nodding, if nodding, then often loosely and openly racemose (or becoming so) or, if flowers retrorsely imbricate, then mostly less than 14 mm; stipes 0–16 mm, or gynophores 0.3–11 mm.	→ 18
18. Calyces 8.3–15.1 mm, sparsely white-hirsute, gibbous-saccate at base behind pedicel; legumes fleshy becoming spongy and honeycombed (walls 2.5–3 mm thick, translucent), bilocular.	A. tennesseensis
18. Calyces 2.3–10.1 mm, strigose or villous with white and/or black hairs, sometimes nearly glabrous, not gibbous-saccate behind pedicel (except A. bisulcatus); legumes mostly papery or papery-membranous, sometimes fleshy becoming leathery, unilocular to bilocular.	→ 19
19. Legumes bilocular, 3-sided compressed; plants of woodlands, brushy, or open areas.	→ 20
20. Plants 40–90 cm; flowers 11.5–13.5 mm; legumes incurved-ascending, linear-ellipsoid, (27–)30–37(–40) × 4–5 mm.	A. glycyphyllos
20. Plants (1–)3–30(–55) cm; flowers 4.5–8.2 mm; legumes pendulous, linear-oblong or -oblanceolate, ellipsoid, or oblong-ellipsoid, 4–30 × 2–4.5 mm.	→ 21
21. Plants (15–)20–55 cm; legumes 15–30 mm; ec, ne Arizona, wc New Mexico.	A. egglestonii
21. Plants 1–30 cm; legumes 4–16 mm; California, Idaho, Nevada, Oregon, Washington.	→ 22
22. Plants 1–3(–7) cm; stems few to several, erect or ascending, densely tufted; caudex with thatch of persistent leaf bases; legumes 4–7 × 2–3 mm; Owyhee County, Idaho, ec Humboldt County, Nevada.	A. yoderwilliamsii
22. Plants 3–30 cm; stems several to numerous, prostrate, spreading, or ascending, not densely tufted, some internodes well developed; caudex without thatch of persistent leaf bases; not of Owyhee County, Idaho, Humboldt County, Nevada.	→ 23
23. Legumes 9–16 × 3–4.5 mm; elevation 600–900(–1000) m; sw Idaho, Malheur County, Oregon.	A. mulfordiae
23. Legumes 6–10.5 × 2–3 mm; elevation 2100–2700 m; Mono County, California, adjacent Nevada.	A. johannis-howellii
19. Legumes mostly unilocular, subunilocular, or sub-bilocular (incompletely bilocular in A. rusbyi), laterally compressed, obcompressed, or flattened, if 3-sided, of mesophytic or alpine habitats.	→ 24
24. Flowers nodding and retrorsely imbricate; legumes with contrasting faces, dorsal face with raised sutures between parallel depressions, ventral face convexly rounded; selenophytes; c Nevada eastward, Arizona north to British Columbia, east to Manitoba.	A. bisulcatus
24. Flowers usually not nodding (except nodding in A. leibergii), not retrorsely imbricate and obviously racemose; legumes without contrasting faces; not selenophytes; Alaska to Newfoundland, south to Arizona.	→ 25
25. Legumes laterally compressed or flattened, unilocular.	→ 26
26. Legumes ascending, humistrate, coiled in 0.5–1 spiral, gynophores 4–10 mm; racemes 1–5-flowered; se Alaska, sw Yukon, British Columbia.	A. nutzotinensis
26. Legumes pendulous, deflexed, or incurved-ascending, not humistrate, straight to slightly curved, or incurved through 0.25 spiral, stipes (0–)0.6–16 mm; racemes (1–)3–35-flowered; Yukon south to Arizona.	→ 27
27. Legumes incurved-ascending; leaflets 9–13, blades broadly obovate-cuneate or -flabellate; Lahontan Basin, Nevada.	A. porrectus
27. Legumes pendulous or deflexed; leaflets (3 or)5–23, blades linear, narrowly oblong, elliptic, oblanceolate, oval, or obovate; not of Lahontan Basin, Nevada.	→ 28
28. Corollas purple or suffused with purple; stipules not blackened on drying; Montana, n Idaho, and British Columbia and Alberta, along Continental Divide.	A. bourgovii
28. Corollas ochroleucous, or if purple (A. inversus, A. wingatanus, and some A. multiflorus) not near the Continental Divide in British Columbia, Alberta, Montana or Idaho; stipules blackened on drying or not.	→ 29
29. Stipules and ripe legumes commonly black or blackish; racemes often paired in leaf axils; flowers 6–9(–11) mm; legumes 7–17 × 2.5–4.5 mm.	A. multiflorus
29. Stipules and ripe legumes brown, stramineous, or purplish; racemes 1 per leaf axil; flowers (5.5–)9.4–17.5 mm; legumes 9–43 × 3–6.5 mm.	→ 30
30. Herbage, pedicels, and calyx villous-villosulous with ascending, spreading and incurved, or curly hairs; calyx tube 5.2–7 × 3.5–4.5 mm; upper Sacramento and Klamath valleys, Shasta County, California to s Jackson County, Oregon.	A. californicus
30. Herbage, pedicels, and calyx strigulose with appressed or subappressed hairs, or subglabrous; calyx tube 1.5–5.5 × 1.2–3.5 mm (rarely longer and wider in A. filipes); widespread.	→ 31
31. Stems often distinctly flexuous, from subterranean caudex; flowers 5.5–8 mm; ne Arizona, sw Colorado, nw New Mexico, se Utah.	A. wingatanus
31. Stems not or only indistinctly flexuous, caudex superficial; flowers 9.4–15 mm; w Utah to British Columbia southward.	→ 32
32. Leaflets (5–)9–23; flowers whitish or cream, keel petals abruptly incurved through 95–120°, about as long as claws; legume body never mottled, glabrous or strigulose; British Columbia southward to California, eastward to Idaho and w Utah.	A. filipes
32. Leaflets 5–11; flowers pinkish red with whitish to buff banner and wing tips, keel petals incurved through 40–85°, longer than claws; legumes strigulose or, if glabrous, then mottled; Modoc to Siskiyou and Lassen counties, California.	A. inversus
25. Legumes usually 3-sided or dorsiventrally compressed, subterete, obcompressed, or laterally compressed, when laterally compressed, then swollen and subunilocular or incompletely bilocular.	→ 33
33. Racemes loosely (1 or)2–18(–20)-flowered; flowers ascending.	→ 34
34. Plants delicate (slender-stemmed); stems sprawling; racemes (1 or)2 or 3(–5)-flowered; moist montane meadows; Colorado, n Idaho, w Montana, Wyoming.	A. leptaleus
34. Plants often somewhat coarse; stems prostrate to ascending; racemes (2–)4–20-flowered; forests, meadows, sandy soils, ridges, sagebrush flats; Alaska east to Newfoundland, south to Colorado.	→ 35
35. Stipes 1–1.5 mm; stems prostrate (underground for 1–9 cm); flowers 9–9.8 mm; corollas yellowish (drying ochroleucous); legumes (13–)15–23 × 3.3–4 mm, 3-sided compressed; Little Kern River Basin, Tulare County, California.	A. shevockii
35. Stipes 4–12 mm (1–2 in A. ertterae) or gynophores 0.3–1 mm; stems prostrate to ascending; flowers (7–)10–19 mm; corollas greenish white, ochroleucous, or pink-purple and sometimes partly white; legumes (4.5–)16–40(–43) × (2.2–)5–12 mm, slightly obcompressed, 3-sided or dorsiventrally compressed, or terete; Alaska to Newfoundland, south to Colorado.	→ 36
36. Stipes or gynophores 0.3–2 mm.	→ 37
37. Corollas pink-purple or partly white; legumes ascending to spreading, (4.5–)7–10(–12) × (2.2–)3–4.5 mm, gynophores 0.3–1 mm; mesic sites; widespread, not in California.	A. bodinii
37. Corollas ochroleucous; legumes pendulous (humistrate), 16–22 × 7–9 mm, stipes 1–2 mm; xeric habitats; Walker Pass, Kern County, California.	A. ertterae
36. Stipes (4–)8–12 mm.	→ 38
38. Legumes obliquely ovoid or ovoid-acuminate, inflated but not bladdery, slightly obcompressed, (10–)13–24(–32) × 6–12 mm, set at an angle to the stipe; Sierra Nevada, California, adjacent Nevada.	A. bolanderi
38. Legumes obliquely oblong or clavate-ellipsoid, subterete to somewhat obcompressed becoming dorsiventrally compressed, 20–40(–43) × 5–8.5(–9) mm, not set at an angle from the stipe; Los Angeles and San Bernardino counties, California.	A. bicristatus
33. Racemes (6–)10–45-flowered, at least some racemes with more than 16 flowers; flowers ascending to nodding.	→ 39
39. Legumes erect; corollas whitish (immaculate); flowers (10.8–)11.6–16.4 mm; peduncles and racemes together equaling or surpassing leaves; Columbia River valley in Chelan, Douglas, Grant, and Kittitas counties, Washington.	A. leibergii
39. Legumes pendulous, spreading or descending; corollas usually purple, pink-purple, pink, or whitish and lilac- or lavender-tinged or -tipped, sometimes ochroleucous, rarely white; flowers 6–13.8(–14.8) mm; peduncles and racemes together usually shorter than stems; widespread.	→ 40
40. Corollas ochroleucous; leaflet blades of proximalmost leaves suborbiculate, broadly obovate, or oblong and apex often retuse-emarginate; Otero County, New Mexico.	A. altus
40. Corollas usually purple, pink-purple, pink, or whitish, sometimes lilac- or lavender-tinged; leaflet blades of proximalmost leaves narrower, linear to ovate, oblong, elliptic or obovate, apex often obtuse to acute; widespread.	→ 41
41. Flowers 6–7.2 mm; racemes (7–)12–40-flowered, axis elongating to (2.5–)4–18(–22) cm in fruit; seeds 6–13; nc Arizona, sw Colorado, c, nw New Mexico.	→ 42
42. Leaflets (11–)17–25; legumes black-strigulose, stipes 2.2–5 mm; nc Arizona.	A. rusbyi
42. Leaflets 7–11; legumes glabrous, stipes (1–)1.2–2 mm; sw Colorado, New Mexico.	A. proximus
41. Flowers 7–13.8(–14.8) mm (rarely as short as 6.2 mm in A. alpinus); racemes 3–26(–40)-flowered, axis elongating to (0.5–)1–15(–20) mm in fruit; seeds 5–25; widespread.	→ 43
43. Flowers 7–11 mm; racemes 7–26-flowered, axis elongated in fruit.	A. flexuosus
43. Flowers (6–)7–14.5 mm; racemes 2–40-flowered, axis little or not elongated in fruit.	→ 44
44. Caudex subterranean; keel somewhat longer than wings and subequal to banner; legumes sulcate abaxially.	A. alpinus
44. Caudex superficial or barely subterranean; keel shorter than wings; legumes flattened or depressed but not sulcate abaxially.	→ 45
45. Proximal stipules connate-sheathing; wing apex obtuse.	A. robbinsii
45. Proximal stipules clasping but not connate or shortly connate proximally; wing apex bidentate.	A. australis

Key to Species of Group 6

1. Legumes globose, subglobose, oblong-ellipsoid, or obliquely ovoid-oblong, fleshy, terete, slightly dorsiventrally compressed, or ± obcompressed, bilocular; stems sprawling-decumbent or ascending and radiating.	→ 2
2. Legumes glabrous, valves differentiated into double envelope separated by air space; Rutherford County, Tennessee	A. bibullatus
2. Legumes strigulose or pilosulous, valves not differentiated into double envelope; North Dakota and Montana south to Texas and Colorado.	A. plattensis
1. Legumes linear to globose, leathery to membranous, sometimes fleshy, 3-sided, dorsiventrally, or laterally compressed or flattened, or subterete, bilocular to unilocular; stems erect to prostrate, sometimes sprawling.	→ 3
3. Flowers ascending or erect, densely racemose (subcapitate); caudex subterranean.	→ 4
4. Stems 9–43 cm; corollas usually pink-purple, sometimes ochroleucous or nearly white; leaflets usually 13–23; legumes oblong-ellipsoid, scarcely swollen, obtusely 3-sided, sulcate abaxially.	A. agrestis
4. Stems 30–90(–130) cm; corollas ochroleucous; leaflets 17–29(–31); legumes broadly obovoid or subglobose, inflated but firm, sulcate adaxially.	A. cicer
3. Flowers erect to nodding, if erect then often soon spreading or declined and loosely racemosely arranged (dense heads in A. austiniae); caudex usually superficial.	→ 5
5. Flowers erect-ascending, in dense, ovoid or subglobose heads; legumes 5.5–7 × 3–3.5 mm, ± included in calyx; Lake Tahoe, El Dorado, Nevada, and Placer counties, California, and Washoe County, Nevada.	A. austiniae
5. Flowers erect to nodding, if erect-ascending then often soon spreading or declined and loosely racemose; legumes 4–60 × 1.2–35 mm, not usually included in calyx; widespread.	→ 6
6. Racemes loosely (rather densely in A. ravenii) (1–)3–6(–8)-flowered; plants from branched subterranean caudex; montane or arctic habitats.	→ 7
7. Underground stems 1–6 cm; corollas whitish, banners lilac-veined, recurved through 80–90°; Sierra Nevada, e Fresno, w Inyo, w Mono counties, California.	A. ravenii
7. Underground stems 6+ cm (1.5–9 cm in A. polaris); corollas whitish, pink-purple, or lilac, banners recurved or reflexed through 50°; interior and n Alaska, Rocky Mountains, Colorado, Idaho, Montana, and Wyoming.	→ 8
8. Legumes ovoid, turgid or bladdery, (15–)18–43 × 4.5–12(–15) mm; corollas usually pink-purple, rarely white; Alaska.	A. polaris
8. Legumes ovoid, lanceoloid, oblong, or ellipsoid, 3-sided compressed or obcompressed (not bladdery), 6.5–14 × 2.5–4 mm; corollas whitish, pink-purple, or lilac; Colorado, Idaho, Montana, Wyoming.	→ 9
9. Corollas white, keel petals 6–7.5 mm; herbage green; legumes pendulous, oblong- or lanceoloid-ellipsoid, slightly decurved; moist montane meadows.	A. leptaleus
9. Corollas pink-purple, lilac, or whitish, keel petals 9–10 mm; herbage ashy gray; legumes ascending (humistrate), obliquely ovoid, lanceoloid-ovoid, or ovoid-ellipsoid, slightly incurved; alpine tundra.	A. molybdenus
6. Racemes (1–)5–45(–125)-flowered; plants from branched or unbranched subterranean or superficial caudex, or from a taproot; widespread habitats.	→ 10
10. Flowers (initially) and legumes erect-ascending; proximal peduncles and racemes together much shorter than stems; e, ec Alaska, s Yukon.	A. williamsii
10. Flowers and legumes mostly pendulous, spreading, reflexed, deflexed, or ascending, when erect, peduncles and racemes together longer than stems; widespread.	→ 11
11. Flowers ascending, sometimes spreading, and legumes erect, sometimes spreading, proximal peduncles and racemes together longer than stem, axis (2.5–)3–25 cm.	→ 12
12. Flowers 7–11 mm; corollas pink-purple, marcescent; legumes 5.5–8 × 2.3–3.4 mm; seeds 4–6; selenophytes; ne Arizona, se Utah.	A. moencoppensis
12. Flowers (13.2–)14–25.5 mm; corollas usually cream, white, or whitish, sometimes with purple tips, deciduous; legumes (10–)15–25 × 4.3–11 mm; seeds 15–35; not selenophytes; Pacific Northwest.	→ 13
13. Legumes usually villous-pilose or hirtellous, sometimes glabrescent; calyces (10–)11–15 mm, lobes (2.6–)4.6–6.7(–7.5) mm; within and near Columbia Gap, Wasco and Hood River counties, Oregon, and Klickitat County, Washington.	A. hoodianus
13. Legumes glabrous or strigulose; calyces 4.9–9.2(–12.2) mm, lobes 1.3–5.1 mm; Idaho, Oregon, Washington.	→ 14
14. Banner recurved through 30–45°, oblanceolate or broadly rhombic-oblanceolate, 16–25.5 mm, apex emarginate; calyx lobes 1.3–3(–4) mm; legumes 4.3–8 mm wide; Benton County, Washington, and trans montane Oregon (Wasco to Baker County), se to sw Idaho.	A. conjunctus
14. Banner recurved through 90°, oblong-oblanceolate, rhombic-oblanceolate, elliptic, oblong-ovate, or somewhat quadrately ovate-cuneate, (13.2–)14–20.7 mm, apex usually deeply notched; calyx lobes (2.4–)2.7–5.1 mm; legumes (5–)6–11 mm wide; Kittitas, Klickitat, and Yakima counties, Washington.	A. reventiformis
11. Flowers and/or legumes usually spreading or declined ultimately, racemes shorter or axis of longest peduncle and raceme together shorter than stem, axis 0.2–30 cm in fruit.	→ 15
15. Plants 2–9(–23) cm, tuft- or mat-forming, subacaulescent or short caulescent; sandy habitats; n Arizona, se Nevada, nw New Mexico, s Utah.	→ 16
16. Calyces 2–3.5 mm, tubes 1.2–2.5 mm; flowers 4–6.2 mm; New Mexico.	→ 17
17. Flowers 5–6.2 mm; legumes 8–14 mm, stipes 0.5–0.8 mm; Lincoln County.	A. kerrii
17. Flowers 4–5 mm; legumes 9–9.8 mm, stipes 0.3–0.6 mm; McKinley County.	A. heilii
16. Calyces 5.5–18 mm, tubes 3–13.5 mm; flowers 9–26 mm; Arizona, Nevada, New Mexico, Utah.	→ 18
18. Calyx tubes 6.5–13.5 mm; flowers 18–26 mm; keel petals concealing style; legumes obliquely ovoid-oblong, dorsiventrally compressed, fleshy becoming somewhat woody, unilocular; n Arizona, se Nevada, nw New Mexico, s Utah.	A. zionis
18. Calyx tubes 3–4 mm; flowers 9–12 mm; keel petals not concealing style; legumes ellipsoid, bladdery-inflated, papery, bilocular; interdune valleys and sandy sites below White and Vermillion cliffs, Kane and Washington counties, Utah, and Coconino County, Arizona.	A. striatiflorus
15. Plants (0.5–)3–80(–110) cm, usually strongly caulescent, sometimes acaulescent, subacaulescent, or short caulescent; marshy, desert, sandy, woodland, or mountain habitats; widespread.	→ 19
19. Racemes densely spikelike and flowers declined and retrorsely imbricate; axis 2.5–8(–9.5) cm in fruit; coastal California, Humboldt to Orange counties.	A. pycnostachyus
19. Racemes loosely flowered, or if densely flowered then flowers not declined or retrorsely imbricate; axis 0.2–30 cm in fruit; n, w, s North America.	→ 20
20. Legumes laterally compressed or flattened, bicarinate and unilocular.	→ 21
21. Legumes 3.5–15 × 1.8–4.5 mm; seeds 4–8(–11).	→ 22
22. Apex of leaflets acute, obtuse, or retuse; legumes glabrous; ne Arizona, sw Colorado, nw New Mexico, se Utah.	A. wingatanus
22. Apex of leaflets usually acute; legumes strigose; Saskatchewan to British Columbia south to South Dakota, Wyoming, and Idaho.	A. vexilliflexus
21. Legumes 11–50(–53) × 2–9 mm; seeds (6–)8–26.	→ 23
23. Corollas pink-purple; flowers (13–)14–20 mm; legumes erect, stiffly leathery to somewhat woody; selenophytes.	A. toanus
23. Corollas ochroleucous, whitish, or greenish white, often tinged or veined with purple or pink; flowers 5.3–13.5 mm; legumes ascending, pendulous, spreading, or declined, papery; not selenophytes.	→ 24
24. Flowering stems accompanied by short, sterile branches forming a tuft of sub-basal leaves; keel apex beaklike.	A. miser
24. Flowering stems not with sub-basal tufts; keel apex broadly triangular.	→ 25
25. Plants from deep subterranean caudex; legumes (13–)25–50(–53) × 2.3–5 mm, linear, narrowly oblong, or oblanceoloid; dry communities.	A. convallarius
25. Plants from shallow subterranean or superficial caudex (with tuberous taproot); legumes 10–17 × 2.7–4 mm, narrowly oblong; moist, saline meadows, ditches, swales.	A. diversifolius
20. Legumes terete, 3-sided compressed, obcompressed, bladdery-inflated, or dorsiventrally compressed, or bilocular or sub-bilocular, when laterally compressed and unilocular, then valves convex or with a ridge parallel to the adaxial suture, or not bicarinate.	→ 26
26. Calyces 8.3–15.1 mm, sparsely white-hirsute, gibbous-saccate behind pedicels; legumes fleshy becoming spongy (walls 2.5–3 mm thick, alveolate-rugulose when ripe), bilocular; n Alabama, c Illinois, c Tennessee.	A. tennesseensis
26. Calyces 2.1–8.2(–13) mm, strigose, pilosulous, villosulous, or glabrous, not gibbous-saccate behind pedicels; legumes papery, membranous, fleshy, or leathery, unilocular to bilocular; n, w, sw North America.	→ 27
27. Plants often densely gray-villosulous, stems sometimes more densely pubescent basally; legumes 3-sided, bilocular (except unilocular in A. microcystis).	→ 28
28. Flowers 9–17.5 mm; legumes 10–20 × 3–5.5 mm; seeds (10–)12–20; California, Nevada.	→ 29
29. Plants from superficial caudex, densely white-tomentose to base; calyces 6.2–8.2 mm; keel petals 6.6–9 mm; seeds (10–)12–16; California (Mono to Modoc counties), w Nevada.	A. andersonii
29. Plants from subterranean caudex, underground for 0.5–5.5 cm where glabrous; calyces 8.6–13 mm; keel petals 10–12.2 mm; seeds (14–)16–20; e foothills, Sierra Nevada, near Lone Pine, Inyo County, California.	A. sepultipes
28. Flowers 4.5–7.8(–8.3) mm; legumes 5–12(–15) × 2–4.2 mm; seeds 6–10; British Columbia to California, east to Montana.	→ 30
30. Legumes plumply ellipsoid, obovoid-ellipsoid, or subglobose, bladdery-inflated, 5–12(–14) × 4–7 mm; se British Columbia, n Idaho, wc Montana, ne Washington.	A. microcystis
30. Legumes ellipsoid, lanceoloid-ellipsoid, or lenticular-oblong, 3-sided or laterally compressed, 5–8.5(–9) × 2–3 mm; California, Idaho, Oregon, Washington.	→ 31
31. Stems erect or ascending, densely white-tomentose proximally; plants (10–)15–30 cm; leaves 3.5–9(–10.5) cm; leaflets 11–19(–23), blades (3–)5–15(–18) mm; racemes (5–)10–25-flowered, axis (1.5–)3–10.5 cm in fruit; sc Idaho to e Oregon, and c, sc Washington.	A. caricinus
31. Stems ascending and diffusely spreading, villosulous; plants 9–18(–25) cm; leaves 1.2–3.5 cm; leaflets 7–15, blades 2–10 mm; racemes 5–10-flowered, axis 0.4–1.6 cm in fruit; ne California.	A. lentiformis
27. Plants variously pubescent (including strigulose, strigose, pilosulous, villosulous, hirsutulous, hirtellous, or tomentulose) but not densely gray-villosulous; legumes unilocular or bilocular, when bilocular then not 3-sided-compressed.	→ 32
32. Plants delicate, from a subterranean caudex; racemes loosely (1 or)2 or 3(–5)-flowered; montane Colorado, ec Idaho, disjunct in w Montana, Wyoming.	A. leptaleus
32. Plants usually slender or robust (delicate in A. pulsiferae), from a subterranean or superficial caudex; racemes (1–)5–90(–125)-flowered; n, w North America.	→ 33
33. Legumes ovoid or ellipsoid, bladdery-inflated, 20–35 × 12–26 mm, bilocular; racemes (4–)6–10(–13)-flowered; flowers 6.4–8.3 mm; Custer and Lemhi counties, Idaho.	A. amblytropis
33. Legumes linear to cylindroid-globose, including ovoid and ellipsoid, compressed, terete, or bladdery-inflated, 3.3–55(–60) × (1.5–)2.3–27(–35) mm, usually unilocular, sometimes subunilocular, sub-bilocular, or bilocular, when bilocular then not bladdery-inflated (A. webberi inflated but not bladdery); racemes 1–90(–125)-flowered; flowers 4.4–24 mm; not of Custer or Lemhi counties, Idaho.	→ 34
34. Legumes strongly curved downward, linear-oblong or linear-ellipsoid, 13–25 × 2.3–3 mm, 3-sided compressed; flowers 5.2–7.7 mm; plants 10–28 cm; Coconino, Gila, and Yavapai counties, Arizona.	A. recurvus
34. Legumes usually straight or incurved or slightly so, when decurved usually broader (oblong, ellipsoid, ovoid-, clavate-, cylindroid-, or lanceoloid-ellipsoid, oblanceoloid, obovoid, lenticular, or subglobose), 3.3–55(–60) × (1.5–)2.3–27(–35) mm, usually subterete, obcompressed, laterally or dorsiventrally compressed, or bladdery-inflated, when 3-sided then obscurely so; flowers (4.1–)5.5–18.8 mm; plants 1–120 cm; n, w North America.	→ 35
35. Plants from subterranean caudex, underground for 1.5–10(–18) cm; corollas whitish, tinged with dull lilac; legumes (7–)9–15 × 3–6 mm, ± bilocular; se Arizona, sw New Mexico.	A. cobrensis
35. Plants from superficial or subterranean caudex, when subterranean then underground for 1–40 cm; corollas pink-purple, ochroleucous, yellowish, or white; legumes 3.5–55(–60) × 1.2–27 mm, usually unilocular, sometimes subunilocular, sub-bilocular or bilocular; n, w North America.	→ 36
36. Plants acaulescent or subacaulescent, usually dwarf, forming mats, cushions, clumps, or tufts (except A. pulsiferae), 1–20(–30) cm.	→ 37
37. Plants densely clump-, cushion-, or tuft-forming, caudex branches with thatch of marcescent leaf rachises; sagebrush communities.	A. jejunus
37. Plants loosely clump-forming (except densely in A. platytropis) or mat- or tuft-forming, caudex branches often without thatch of marcescent leaf bases; various communities.	→ 38
38. Plants forming compact mats or cushions; slopes of degraded sandstone or base of sandstone buttes.	→ 39
39. Leaves (1–)1.5–5.5 cm; leaflets (7 or) 9–15, not crowded, blades 0.7–10 mm; racemes 4–10-flowered.	A. chuskanus
39. Leaves 0.4–1(–2) cm; leaflets (3 or)5–9, subpalmately crowded, blades 1–3.5(–6) mm; racemes 1–3(–5)-flowered.	A. micromerius
38. Plants loosely tuft-forming, or if densely so, not mat-forming; various habitats.	→ 40
40. Legumes deflexed, cylindroid-ellipsoid, 9–17 × 4–6 mm, obtusely 3-sided, strigulose; c New Mexico to w Texas.	A. pictiformis
40. Legumes ascending, spreading, or declined, sometimes humistrate, oblong, ovoid-ellipsoid or -lenticular, or subglobose, 3.3–20(–22) × 1.5–22 mm, usually bladdery-inflated or dorsiventrally compressed, sometimes slightly 3-sided compressed, villous, strigose, or strigulose; Montana to Colorado west to Washington and California.	→ 41
41. Racemes 2–5-flowered; legumes narrowly oblong, 12–20 × 3.5–5 mm, slightly 3-sided; plants 4–7(–10) cm, forming small tufts; Mesa Verde, Montezuma County, Colorado.	A. deterior
41. Racemes (best developed) 5–13-flowered; legumes 3.5–33 × 1.5–22 mm, ovoid or subglobose and bladdery-inflated, sometimes lanceoloid-ovoid or obliquely ovoid-acuminate, if obscurely 3-sided then ovoid-lenticular; plants 1–25 cm, sometimes forming cushions or mats; Montana to Utah west to California and Washington.	→ 42
42. Flowers 10–13 mm; corollas whitish, tinged with pinkish lavender; Mono Lake in Mono County, California.	A. monoensis
42. Flowers 4.4–10(–12) mm; corollas whitish, yellowish, ochroleucous, or pink-purple; w United States.	→ 43
43. Legumes 3.3–4.5 × 1.5–4.2 mm; Lassen County, California, Harney County, Oregon.	A. tegetarioides
43. Legumes 8–33 × (5–)6–22 mm; w United States.	→ 44
44. Caudex subterranean or, if superficial, with many naked, slender branches below ground, stems underground for 2–9(–12) cm; corollas whitish or yellowish, banners and keel tips with lilac veins; legumes villosulous or hirtellous; Lassen to Sierra counties, California, adjacent Washoe County, Nevada, disjunct on Mt. Adams, Klickitat County, Washington.	A. pulsiferae
44. Caudex superficial (sometimes soboliferous in A. limnocharis); corollas pink-purple, whitish, or ochroleucous; legumes strigose or strigulose; w United States.	→ 45
45. Legumes 15–33 × 10–22 mm, bilocular or semibilocular; montane summits; Montana to Utah west to Idaho, Oregon, and California.	A. platytropis
45. Legumes 9–18(–23) × 7–14(–15) mm, unilocular; plateaus, mountains, lakeshores; sc Utah.	→ 46
46. Stipules connate-sheathing proximally, distinct distally; legumes thin and translucent, with gynophores 0.1–0.8 mm.	A. perianus
46. Stipules connate-sheathing throughout; legumes membranous and opaque, sessile.	→ 47
47. Flowers 6.2–7.5 mm; corollas ochroleucous or pink-purple with purple wing tips.	A. limnocharis
47. Flowers 7.2–8 mm; corollas pink-purple with white wing tips.	A. montii
36. Plants strongly caulescent, not forming mats, cushions, clumps, or tufts, (7–)20–100(–120) cm.	→ 48
48. Racemes 2–18-flowered (to 33 in A. praelongus).	→ 49
49. Flowers 13–17.6 mm; Plumas and Sierra counties, California.	A. webberi
49. Flowers 5.6–14(–16) mm; Arizona, Colorado, Utah.	→ 50
50. Flowers 11–14(–16) mm; corollas pale lemon yellow, keel petals immaculate; plants selenophytes; w Iron and Beaver counties, Utah.	A. praelongus
50. Flowers 5.6–11 mm; corollas whitish tinged with lilac, or ochroleucous suffused with purple; plants not selenophytes; Arizona, Colorado.	→ 51
51. Flowers 5.6–5.8 mm; legumes ellipsoid or lanceoloid-ellipsoid, 6–9.5 mm, obcompressed, stipes ca. 0.4 mm; near Gunnison, Colorado.	A. microcymbus
51. Flowers 8–11 mm; legumes oblong-ellipsoid, 21–34 mm, terete or dorsiventrally compressed, stipes to 1 mm; n Coconino County, Arizona.	A. atwoodii
48. Racemes (3–)15–90(–125)-flowered.	→ 52
52. Flowers (4.1–)5.3–8.4 mm; plants of Great Plains or montane and arctic.	→ 53
53. Calyces 3.3–5.4 mm; legumes (4–)5–12(–13) mm, subsymmetrically or obliquely ovoid-ellipsoid, laterally compressed, strigose-pilosulous, sub-bilocular; montane or arctic, Colorado and Washington north to Alaska, east to Nova Scotia.	A. eucosmus
53. Calyces 2.1–3.3 mm; legumes (4–)4.3–8(–9) mm, obliquely subglobose, plumply ovoid, or ovoid-ellipsoid, obcompressed, strigulose to villosulous, unilocular; high plains, Texas to Saskatchewan.	A. gracilis
52. Flowers (5.1–)8.4–21 mm; plants of woodlands, beach or lakeshores, desert scrub, rocky slopes, or mountain brush communities.	→ 54
54. Legumes swollen, slightly bladdery, somewhat 3-sided, (4.5–)7–10(–12) × (2.2–)3–4.5 mm; seeds 2–10; plants from superficial or ± subterranean caudex; stems spreading or prostrate.	A. bodinii
54. Legumes terete, subterete, obcompressed, dorsiventrally or laterally compressed, 3-sided, or bladdery-inflated, (5–)10–55(–60) × (2.7–)4.5–27(–35) mm, when less than 10 mm then bladdery-inflated or subterete, not 3-sided; seeds (6–)10–42; plants mostly from deeply subterranean caudex (superficial in A. microcystis, A. miguelensis, and A. nuttallii); stems erect to prostrate or sprawling.	→ 55
55. Legumes 20–55 × (5–)6–10 mm, obcompressed; flowers (12–)13.5–18 mm; stems ± strongly flexuous; Inyo County, California, northward to Pershing and Washoe counties, Nevada, and in Nye County, Nevada.	A. casei
55. Legumes 5–32(–60 in A. nuttallii) × 2.7–27(–35) mm, subterete, inflated, or laterally compressed; flowers 5.1–16(–21) mm; stems usually not flexuous, when flexuous then flowers less then 12 mm; n, w North America.	→ 56
56. Legumes (3–)4–12 mm wide, stiffly cartilaginous to leathery; Oklahoma to Utah and Arizona.	→ 57
57. Legumes cartilaginous, sometimes distinctly inflated, subsessile or stipitate, (3–)4–12 mm wide.	A. hallii
57. Legumes leathery, somewhat inflated, (not bladdery), ± sessile, (4.5–)5–9.5 mm wide.	A. puniceus
56. Legumes 2.7–27 mm wide, papery, papery-membranous, thin, or fleshy; n, w North America.	→ 58
58. Legumes subterete or somewhat flattened, 2.7–9 mm wide.	→ 59
59. Stems silky-canescent, hairs appressed, incurved-ascending, or curly.	A. flexuosus
59. Stems strigulose-villosulous or hirsutulous, hairs stiff, straight, spreading or subretrorse.	A. subcinereus
58. Legumes tumid or bladdery-inflated, (3.5–)9–27 mm wide.	→ 60
60. Legumes 5–12(–14) × 4–7 mm; flowers 5.1–7.5(–8.3) mm; Montana to Washington into British Columbia.	A. microcystis
60. Legumes 12–55(–60) × (3.5–)9–27 mm; flowers 6.4–16 mm; Colorado and New Mexico west to California.	→ 61
61. Legumes 16–55(–60) × (9–)13–27 mm; California.	→ 62
62. Legumes 16–26 × (9–)13–23 mm; racemes 10–30-flowered; Anacapa, San Clemente, San Miguel, Santa Cruz, and Santa Rosa islands, California.	A. miguelensis
62. Legumes (20–)25–55(–60) × 15–27 mm; racemes (15–)20–90(–125)-flowered; coastal c California.	A. nuttallii
61. Legumes 12–32 × 3.5–20 mm; Colorado and New Mexico west to Arizona and Nevada.	→ 63
63. Stems, calyces, and legumes strigulose or strigose with appressed hairs; apex of keels triangular and beaklike; legumes ovoid, ellipsoid, or subglobose, 12–22 mm wide; plants of sandy desert shrublands.	A. fucatus
63. Stems, calyces, and legumes strigulose-villosulous or hirsutulous with spreading or subretrorse hairs; apex of keels broadly deltate; legumes ovoid to ellipsoid or cylindroid-ellipsoid, 3.5–13 mm wide; plants of ponderosa pine, pinyon-juniper, aspen, or oak woodlands, or mixed brush communities.	A. subcinereus

Key to Species of Group 7

1. Legumes on stipelike gynophores (joint between gynophore and legume base).	→ 2
2. Caudex deeply subterranean; leaflets (9 or)11–27, closely spaced on rachis; legumes 15–38 × 8–23 mm, unilocular; plants of Uinta Formation limestone, rim of Uinta Basin; Colorado, Utah.	A. lutosus
2. Caudex superficial or aerial; leaflets 3–25(–33), either fewer or widely spaced along rachis; legumes (6–)13–70(–90) × (2.5–)3–13(–45) mm, mostly bilocular or subunilocular, sometimes unilocular; British Columbia south to Arizona, east to Florida, if of Uinta Basin then legumes larger and peduncles subradical.	→ 3
3. Plants acaulescent or subacaulescent, tuft-forming.	→ 4
4. Herbage usually villous to villous-tomentose, sometimes appearing white or grayish; legumes mostly shaggy-villous, sometimes tomentose or villous-hirsute (hairs often concealing surface), not mottled or spotted; British Columbia south to Utah.	A. purshii
4. Herbage strigulose, appearing green or grayish; legumes sparsely strigulose, long silky-pilose, or hirsute (hairs not concealing surface), red-mottled or -spotted; Colorado Plateau.	→ 5
5. Legumes sparsely strigulose; wc, sw Colorado, nw New Mexico, extreme ne San Juan County, Utah.	A. naturitensis
5. Legumes hirsute or long silky-pilose; Arizona, Colorado, New Mexico, Utah.	→ 6
6. Flowers 6–9 mm; n Arizona, wc Colorado, nw New Mexico, se Utah.	A. desperatus
6. Flowers 12–16 mm; n Arizona, near Gateway, Mesa County, Colorado, e Utah.	→ 7
7. Plants 1.5–5 cm; leaves 1.5–5 cm; racemes 2–8-flowered, axis 0.5–2.5 cm in fruit; Navajo County, Arizona, Garfield and Wayne counties, Utah.	A. barnebyi
7. Plants 5–18 cm; leaves 1.5–9 cm; racemes 4–13-flowered, axis 1.5–8 cm in fruit; Mesa County, Colorado, Uintah County, Utah.	A. equisolensis
3. Plants usually caulescent (subacaulescent in A. megacarpus), mostly not tuft-forming, sometimes loosely so (densely so in A. megacarpus).	→ 8
8. Plants 70–150 cm, caudex trunklike; stems fistulose; legumes deflexed, 6.5–9 × (2.5–)3–4 mm, gynophores 0.5–0.7 mm; Los Angeles and Orange counties, California.	A. brauntonii
8. Plants 2–50(–70) cm, caudex not trunklike; stems not fistulose; legumes usually spreading to erect (sometimes pendulous in A. oophorus, or declined or horizontal in A. nutans and A. wetherillii), 13–55(–90) × (2.5–)3.2–17(–45) mm, gynophores 0.4–4(–11) mm; British Columbia south to Arizona, east to Georgia.	→ 9
9. Plants short-lived perennials; blooming throughout the growing season, often with flowers and mature fruit occurring simultaneously; seeds 9–13; on and below sandstone escarpments east of Grand Junction, Colorado.	A. wetherillii
9. Plants annuals, biennials, or perennials, rarely with flowers and mature fruit occurring simultaneously; seeds (7–)12–54; British Columbia south to Arizona, east to Georgia.	→ 10
10. Legumes bladdery-inflated, pale green becoming stramineous, not red or mottled; plants annual, biennial, or short-lived perennial; flowers 7.8–10.4 mm; deserts, s California.	A. nutans
10. Legumes often 3-sided, dorsiventrally, or laterally compressed, when bladdery-inflated, then red- or reddish purple-mottled; plants long- or short-lived perennial; flowers (6.6–)8.5–24(–26) mm; various habitats, widespread, including s California.	→ 11
11. Legumes (20–)24–42 × 3.5–5.5 mm, 3-sided; flowers 7.1–15.7 mm.	→ 12
12. Peduncles 9–20 cm, arising from base or near middle of stem, together with racemes as long as or longer than stems; leaflets (17 or)19–25(or 27); flowers 12.6–15.7 mm; calyx tubes 4.1–5 mm.	A. tricarinatus
12. Peduncles (1.5–)3–10 cm, arising from stem distally, together with racemes much shorter than stems; leaflets (7–)11–17(or 19); flowers 7.1–10.2 mm; calyx tubes 2.7–4.1 mm.	A. bernardinus
11. Legumes 13–70(–90) × (2.8–)3.2–45 mm, dorsiventrally or laterally compressed, bluntly 3-sided, or bladdery-inflated; flowers (6.6–)8.2–24(–26) mm.	→ 13
13. Plants sometimes short-lived perennials; legumes green, not mottled; Great Plains and eastward.	→ 14
14. Herbage hirsute, hairs spreading, often spirally twisted, to 1.1–2 mm; legumes hirsute; leaflets (3–)7–15, thin-textured, larger ones with pinnate venation; corollas pale yellow to greenish ochroleucous; s, e Alabama, east to South Carolina, Georgia, and Florida.	A. villosus
14. Herbage sparsely strigulose to hirsutulous, glabrous, or glabrate, hairs subappressed, to 0.7 mm; legumes glabrous; leaflets (9–)13–27, firm-textured, venation not apparent; corollas pink-purple, cream or whitish, sometimes with dark keel; Great Plains south to Oklahoma, east to Georgia.	→ 15
15. Legumes coarsely reticulate in age; flowers 8.5–11 mm; calyx lobes (1.8–)2.2–2.8 mm.	A. obcordatus
15. Legumes not especially reticulate in age; flowers 8.2–17.4 mm; calyx lobes 1–4 mm.	→ 16
16. Corollas pink-purple, purplish, or whitish; flowers 8.2–15.5 mm; calyx lobes 1–2 mm.	A. distortus
16. Corollas white to greenish white or cream; flowers 11.4–17.4 mm; calyx lobes (2–)2.4–4 mm.	A. soxmaniorum
13. Plants long-lived perennials; legumes red- or reddish purple-mottled; Rocky Mountains and westward.	→ 17
17. Plants loosely tuft-forming, 3–23 cm; flowers 6.6–8.6 mm; e Piute, s Sevier, and w Wayne counties, Utah.	A. serpens
17. Plants densely or not tuft-forming, (3–)15–70 cm; flowers 11–24(–26) mm; British Columbia to California, east to Colorado.	→ 18
18. Legumes (15–)20–30 mm, dorsiventrally compressed, fleshy becoming leathery.	A. beckwithii
18. Legumes (20–)25–70(–90) mm, bladdery-inflated, papery.	→ 19
19. Plants subacaulescent or short caulescent; stems 1–7 cm, internodes mostly concealed by stipules; racemes among leaves, 1–7(or 8)-flowered.	A. megacarpus
19. Plants caulescent; stems (2–)15–25 cm, some internodes elongated and longer than stipules; racemes often extending above leaves, 3–14-flowered.	A. oophorus
1. Legumes on stipes (no joint between stipe and legume base).	→ 20
20. Legumes laterally compressed, mostly unilocular (sub-bilocular in A. australis).	→ 21
21. Wing petals bilobed; legumes appearing sub-bilocular.	A. australis
21. Wing petals entire; legumes unilocular.	→ 22
22. Legumes usually incurved into a hook or sickle, or coiled into a ring or spiral (sometimes ± straight in A. sclerocarpus).	→ 23
23. Calyx tubes 2–2.5 mm, not marcescent; plants from deeply subterranean caudex; seeds 10–16.	A. alvordensis
23. Calyx tubes 4.7–11.9 mm, marcescent; plants from superficial or shallow subterranean caudex (sometimes rhizomatous); seeds 14–36.	→ 24
24. Plants with slender rhizomes; corollas pink-purple; Owyhee County, Idaho.	A. camptopus
24. Plants from superficial or shallow subterranean caudex; corollas ochroleucous, whitish, or lemon yellow; British Columbia and California east to Idaho and Nevada.	→ 25
25. Flowers nodding at anthesis; calyx tubes swollen, strongly oblique or saccate abaxially at base.	A. curvicarpus
25. Flowers ascending at anthesis; calyx tubes not swollen, scarcely oblique and never gibbous proximally.	→ 26
26. Calyces and leaflets mostly with straight, appressed hairs; leaflet blades linear, linear-oblanceolate, or narrowly oblong; legumes lunately or falcately ellipsoid, 6.5–9 mm wide, nearly straight to incurved through 0.5 spiral.	A. sclerocarpus
26. Calyces and leaflets with incumbent or curly hairs; leaflet blades oblong, obovate-cuneate, oblong-oblanceolate, cuneate-oblanceolate, or cuneate-obcordate; legumes linear-oblong or oblong, (2.7–)3.2–7 mm wide, lunate- or hamate-incurved, or coiled through 1.25–2.5 spirals.	→ 27
27. Peduncles 4.5–12 cm; pedicels 1.5–3.5 mm; legumes lunate- or hamate-incurved; s Chelan County, Washington.	A. sinuatus
27. Peduncles (1–)2.5–5(–6.5) cm; pedicels 1–2.5 mm; legumes tightly coiled through 1.25–2.5 spirals, or elaborately and irregularly contorted; Benton, Kittitas, Klickitat, and Yakima counties, Washington.	A. speirocarpus
22. Legumes straight or gradually incurved or decurved (sometimes falcately decurved in A. solitarius).	→ 28
28. Calyces gibbous-saccate; corollas cream to pale lemon yellow; legumes 7–25 × 2.3–4.2 mm, stipes (3.5–)5–15 mm; s British Columbia south to ne Oregon, adjacent Idaho.	A. collinus
28. Calyces not gibbous; corollas whitish, lemon yellow, greenish white to cream, or pink-purple, sometimes tinged lilac or pinkish; legumes 8–40(–45) × 2.4–18(–21) mm, stipes (1–)4–16(–19) mm; Oregon and California east to Wyoming and New Mexico.	→ 29
29. Legumes 8–11 × 2.4–2.8 mm, stipes 4–5 mm; flowers 6.5–7 mm; Klamath County, Oregon.	A. applegatei
29. Legumes 12–40(–45) × 3–18(–21) mm, stipes (1–)6–16(–19) mm; flowers (6.3–)11.3–19 mm; Oregon and California east to Wyoming and New Mexico.	→ 30
30. Legumes erect-ascending, 22–30 × 6–9 mm, stipes 12–16(–19) mm, legumes inverted from twisting of pedicels; Towaoc, Montezuma County, Colorado.	A. tortipes
30. Legumes pendulous or declined, 12–40(–45) × (3–)3.5–18(–21) mm, stipes (1–)4–17 mm, legumes not inverted; Arizona, California, Colorado, New Mexico, Oregon, Utah, Wyoming.	→ 31
31. Legumes (13–)15–40(–45) mm, stipes (6–)6.5–17 mm; corollas greenish white or cream; coastal or near coastal sw California.	A. trichopodus
31. Legumes 12–35 mm, stipes (1–)4–11 mm; corollas ochroleucous, pinkish white, or pink-purple; Arizona, Colorado, Nevada, New Mexico, Oregon, Utah, Wyoming.	→ 32
32. Calyx tubes 2.3–2.8 mm; leaflets 5–9.	A. solitarius
32. Calyx tubes 3.2–6.7 mm; leaflets (1 or)3–19.	→ 33
33. Corollas ochroleucous, tinged or veined with lilac, or pinkish white; flowers 7.3–8.5 mm; stipes 1–1.5 mm; nw Arizona south of Grand Canyon.	A. titanophilus
33. Corollas pink-purple; flowers 12–19 mm; stipes 4–11 mm; sw Wyoming, south to e Utah, w Colorado, ne Arizona, nw New Mexico.	A. coltonii
20. Legumes usually 3-sided or dorsiventrally compressed, obcompressed, inflated, or subterete, rarely laterally compressed, unilocular to bilocular, when laterally compressed or appearing so, then fully bilocular (except unilocular in A. tweedyi where faces strongly convex).	→ 34
34. Legumes inflated, not bladdery, unilocular (or subunilocular in A. praelongus); plants selenophytes.	→ 35
35. Leaflets (1 or)3–13, blades 6–35(–50) mm, rhombic-oval, obovate, or elliptic; legumes sessile or subsessile, cylindroid or subcylindroid, 20–48 × 9–15 mm; corollas white or ochroleucous; Mancos Shale and Morrison formations; Grand and San Juan counties, Utah.	→ 36
36. Flowers 23–34 mm; nw of Moab (Morrison Formation) and Cisco (Mancos Shale) vicinities, Grand County, Utah.	A. sabulosus
36. Flowers 17–19 mm; foothills of La Sal Mountains, Paradox and Morrison formations, Grand and San Juan counties, Utah.	A. iselyi
35. Leaflets (3 or)5–33, blades (1–)2–50 mm, linear, obovate, elliptic, oblong, lanceolate, oblanceolate, obcordate, or suborbiculate; legumes sessile, subsessile, or stipitate, if in Grand or San Juan counties, Utah, then stipes (1.5–)2–8 mm, ellipsoid, oblong- to lanceoloid-ellipsoid, ovoid, cylindroid, obovoid, or subglobose, 12–42 × 5–25 mm; corollas pink-purple, ochroleucous, or white; fine-textured substrates; California to Colorado south to Texas.	→ 37
37. Calyces green or yellowish; corollas ochroleucous or pale lemon yellow, keel often purplish-tipped; legumes fleshy becoming leathery-woody; Colorado and Texas west to Nevada and Arizona.	A. praelongus
37. Calyces often purple, sometimes white; corollas pink-purple, pale greenish yellow, or white, then sometimes tinged purplish; legumes thinly cartilaginous or fleshy to leathery or papery; Colorado west to California.	→ 38
38. Corollas white or pale purple; plants short-lived and flowering first year, or long-lived and forming large clumps; wc Colorado and along San Juan River, San Juan County, Utah.	→ 39
39. Corollas white or tinged purplish; calyces pale purple or whitish; stipes 3–3.5 mm; plants short-lived perennials, often flowering first year, not forming bushy clumps; along San Juan River, San Juan County, Utah.	A. cutleri
39. Corollas white; calyces usually greenish to stramineous, rarely white; stipes 2–2.5 mm; plants long-lived perennials, forming bushy clumps; De Beque, Mesa County, Colorado.	A. debequaeus
38. Corollas pink-, magenta-, or reddish purple (often drying dark purple); plants often long-lived, forming small clumps; Colorado west to California.	→ 40
40. Legumes erect or narrowly ascending; peduncles erect-ascending in fruit; stems erect or incurved-ascending; plants (10–)12–53 cm; nw, nc Arizona, disjunct in se California, wc Colorado, s Nevada, se Utah along Colorado and Green rivers.	A. preussii
40. Legumes spreading, declined, or weakly ascending; peduncles weakly ascending or reclining in fruit; stems erect to ascending or decumbent; plants 8–20 or 15–50(–60) cm; Arizona, California, Colorado, Utah.	→ 41
41. Legumes usually glabrous, rarely minutely scabrid-pubescent; flowers 18–22 mm; plants relatively slender and diffuse, 8–20 cm; wc, sw Colorado, se Utah along Colorado River.	A. eastwoodiae
41. Legumes strigulose; flowers 21–28 mm; plants coarse, clump-forming, 15–50(–60) cm; Imperial, Riverside, and San Diego counties, California, sw Arizona.	A. crotalariae
34. Legumes usually obcompressed, subterete, or 3-sided, dorsiventrally or laterally compressed, when legumes inflated or bladdery, then ± bilocular (± unilocular in A. aequalis, A. ampullarioides, and A. praelongus); plants selenophytes or not.	→ 42
42. Corollas ochroleucous or pale lemon yellow, keel petals often purple-tipped; legumes erect to spreading or declined, fleshy becoming leathery-woody; plants selenophytes.	A. praelongus
42. Corollas pink-purple, whitish, yellow, keel petals maculate or immaculate; legumes pendulous, reflexed, spreading, ascending, or erect, if erect, then not fleshy; plants not selenophytes.	→ 43
43. Legumes bladdery-inflated, spreading or declined, 25–40 × 12–20 mm; flowers 11.5–12 mm; corollas ochroleucous, often lined or tinged purple; Spring (Charleston) Mountains, Clark County, Nevada.	A. aequalis
43. Legumes not bladdery-inflated (except sometimes A. lentiginosus), mostly pendulous, sometimes spreading, erect, ascending, reflexed, or declined, (7–)10–40(–48) × 2.2–10(–19) mm; flowers 5–21.5 mm; corollas pink-purple, whitish, greenish white, yellow, or ochroleucous; Alaska south to Utah, east to Nova Scotia.	→ 44
44. Corollas ochroleucous; legumes (25–)30–40 mm, 3-sided, stipes 5–10(–12) mm; Mesa Verde, Montezuma County, Colorado.	A. schmolliae
44. Corollas pink-purple, whitish, greenish white, yellow, or ochroleucous; legumes (7–)10–30(–48) mm, 3-sided or not, stipes (0–)1–20 mm; Alaska south to Utah, east to Nova Scotia.	→ 45
45. Legumes ascending, 15–21 × 2.8–3.8 mm, 3-sided compressed; flowers 12–14 mm; corollas reddish purple (drying bluish); nw Clark and sw Lincoln counties, Nevada.	A. ackermanii
45. Legumes mostly pendulous to spreading, ascending, or erect, sometimes humistrate, declined, or reflexed; flowers 5–21.5 mm; corollas pink-purple, whitish, greenish white, yellow, or ochroleucous; Alaska south to Utah, east to Nova Scotia.	→ 46
46. Legumes pendulous, obtusely 3-sided, papery-membranous, valves inflexed as hyaline septum, 0.2–2 mm wide; seeds 6–10; mesophytic habitats; Nevada and Colorado north to Arctic and n New England.	A. robbinsii
46. Legumes mostly pendulous to spreading, ascending, or erect, sometimes humistrate, declined, or reflexed, papery, membranous, leathery, woody, subligneous, or fleshy, valves inflexed or not, septum to 6 mm wide; seeds 6–42; xeric habitats; British Columbia south to Texas.	→ 47
47. Herbage softly villous-hirsute or shaggy-villous, hairs minutely dilated at base; flowers nodding; corollas whitish to ochroleucous, keel petals purple-tipped; legumes narrowly oblong to oblanceoloid, obscurely 3-sided compressed, glabrous, bilocular.	A. drummondii
47. Herbage strigulose, villosulous, pilosulous, or tomentulose, not villous- or shaggy-hirsute, hairs not dilated at base; flowers nodding or not; corollas pink-purple, whitish, greenish white, yellow, or ochroleucous; legumes ellipsoid, oblong to lanceoloid, linear, ovoid, or cylindroid, subterete, compressed, or 3-sided, strigulose, villous, hirsutulous, tomentulose, or glabrous, unilocular to bilocular.	→ 48
48. Herbage villous-tomentulose or soft-villosulous, appearing gray or ashy; insular sw California.	→ 49
49. Leaflets 21–29; flowers 14.2–17.5 mm; keel petals 10.2–12.9 mm; legumes villous-tomentulose; Santa Barbara and San Nicolas islands.	A. traskiae
49. Leaflets 11–25; flowers 10.6–12.7 mm; keel petals 9–10 mm; legumes glabrous; San Clemente Island.	A. nevinii
48. Herbage strigulose, villosulous, pilosulous, or tomentulose, usually not appearing gray or ashy; British Columbia south to Texas.	→ 50
50. Stems with proximalmost internodes not or shortly elongated; peduncles sub-basal and appearing scapelike or, if plants caulescent and with axillary peduncles, then herbage villous with hairs 0.8–1.5 mm; Inyo and San Bernardino counties, California, Clark, Esmeralda, and Lincoln counties, Nevada.	A. minthorniae
50. Stems usually with elongated (well-spaced) internodes; peduncles axillary or, if sub-basal, then pubescence different, or not of Inyo and San Bernardino counties, California, Clark, Esmeralda, and Lincoln counties, Nevada.	→ 51
51. Legumes usually erect, rarely deflexed, not humistrate, 3-sided and 2.7–8(–9) mm wide, or obcompressed to inflated and (4.5–)6.5–10(–12) mm wide.	→ 52
52. Plants from subterranean caudex; stems decumbent proximally, erect distally, often fistulose; legumes inflated (turgid), 8–10(–12) mm wide; Triassic Chinle Formation clays, Washington County, Utah.	A. ampullarioides
52. Plants from superficial caudex; stems erect-ascending (except sometimes decumbent in A. scaphoides), not fistulose; legumes usually not inflated (or moderately so in A. scaphoides), 2.7–8(–10) mm wide; Arizona and New Mexico north to Washington and Montana.	→ 53
53. Stipes 6–18 mm, incurved from spreading pedicels, racemes broad and loose.	→ 54
54. Legumes cuneate basally, 3.5–8(–9) mm wide, grooved dorsally, keeled ventrally, septum 0.5–1.2 mm wide; New Mexico and Arizona north to Oregon and Idaho.	A. eremiticus
54. Legumes truncate basally, (4.5–)6.5–10 mm wide, both sutures grooved, septum 1.4–1.8 mm wide; Bitterroot Mountains, ec Idaho, w Montana.	A. scaphoides
53. Stipes 2.5–7 mm, fruits straight, erect in same plane as body and pedicels, legumes appressed or near to raceme axis and fruiting racemes strict and narrow, or if pedicels ascending at a slightly different angle and legumes slightly divergent (as in A. arrectus), then obcompressed.	→ 55
55. Pedicels 0.5–1.2 mm at anthesis, clavately thickened in fruit, 1.5–4 mm; legumes 4.5–6.3 mm wide, obcompressed; ec, se Washington, adjacent Idaho.	A. arrectus
55. Pedicels 0.7–1.9 mm at anthesis, not or only somewhat thickened in fruit; legumes 2.7–4.5 mm wide, obtusely 3-sided or 3-sided compressed; Idaho, Montana, Nevada.	→ 56
56. Legumes obtusely 3-sided, lateral face convex, abaxial face scarcely narrower, grooved or not; flowers nodding; leaflets (15–)19–27(or 29); c Idaho to sw Montana.	A. atropubescens
56. Legumes 3-sided compressed, lateral face flat, abaxial face narrower and grooved; flowers ascending; leaflets 11–19(or 21); Spring (Charleston) Mountains, Nevada.	A. remotus
51. Legumes either humistrately ascending from reclining peduncles, spreading-ascending, or pendulous from ascending pedicels, dorsiventrally, laterally, or 3-sided compressed or subterete, (2–)3.4–21 mm wide.	→ 57
57. Legumes laterally compressed, sutures forming prominent ridges.	→ 58
58. Legumes pendulous; flowers (6.5–)7–10 mm; keel petal apex triangular and subacute; plants from subterranean caudex; Mojave Desert, San Bernardino County, California.	A. jaegerianus
58. Legumes spreading or ascending; flowers 15–22 mm; keel petal apex obtuse; plants from aerial caudex; Kern, Los Angeles, Riverside, San Benito, and Ventura counties, California.	A. pachypus
57. Legumes not laterally compressed (except A. tweedyi, sometimes A. accidens), sutures not forming prominent ridges.	→ 59
59. Stipes (4–)5–20 mm.	→ 60
60. Legumes 3-sided compressed, or 3-sided and laterally compressed, bilocular; w Idaho, adjacent Oregon and Washington.	→ 61
61. Legumes (16–)20–30 × 3–4.5(–5) mm and 5–7-times longer than wide, lateral face flat, abaxial face grooved; herbage and legumes villosulous; leaflet surfaces pubescent; Wasco to Morrow counties, Oregon, and sw Washington.	A. howellii
61. Legumes (25–)30–45 × 2.5–3.3 mm, mostly 10 times longer than wide, lateral face convex, abaxial face narrowly sulcate; herbage and legumes strigulose; leaflet surfaces pubescent abaxially, glabrous adaxially; near common boundary of Idaho, Oregon, and Washington, west to Umatilla County, Oregon.	A. arthurii
60. Legumes subterete or obcompressed (except laterally compressed in A. tweedyi, sometimes A. accidens), valves bilocular or not; California, Idaho, Nevada, Oregon, Washington.	→ 62
62. Calyces 8–10.5 mm; corollas ochroleucous; stipes pilosulous; Columbia and Deschutes valleys, nc Oregon and sc Washington.	A. tweedyi
62. Calyces 5–9.4(–11) mm; corollas whitish, yellowish, or reddish purple; stipes glabrous; California to Washington, east to Nevada and Idaho.	→ 63
63. Legumes subterete and fleshy, becoming slightly laterally compressed and leathery or woody; sw Oregon, adjacent n California.	A. accidens
63. Legumes obcompressed and fleshy becoming woody, papery, leathery, or subligneous, or turgid and somewhat obcompressed and subligneous becoming transversely rugose; California to Washington, east to Nevada, Idaho, and Oklahoma.	→ 64
64. Legumes pendulous, somewhat obcompressed, transversely rugose in age.	A. chinensis
64. Legumes spreading to ascending (humistrate), obcompressed, smooth in age.	→ 65
65. Leaves green; racemes 5–7-flowered, axis 1.5–2 cm in fruit.	A. vallaris
65. Leaves glaucescent; racemes 10–25-flowered, axis 3–12 cm in fruit.	A. cimae
59. Stipes (0–)1–4(–5) mm.	→ 66
66. Legumes usually decurved, adaxial suture convex in profile, or at least beak declined from body.	→ 67
67. Legumes 2.5–4.3 mm wide, unilocular or bilocular, septum (0 or)0.6–2.7 mm wide; se California, sw Idaho, nc, c Nevada, e Oregon.	A. atratus
67. Legumes 4–6.5 mm wide, partially bilocular, septum incomplete to 0.7 mm wide; sw Idaho, n Nevada, se Oregon.	A. salmonis
66. Legumes straight to deeply incurved, either adaxial suture appearing concave or beak curved.	→ 68
68. Legumes usually lunately or falcately curved (sometimes straight in A. congdonii), 10–35 × 2.3–4 mm; corollas yellowish, yellowish or greenish white, greenish ochroleucous, or white, rarely faintly tinged lilac or rose; flowers 6.5–14(–16.6) mm.	→ 69
69. Stipes 2.5–5 mm; corollas yellowish, yellowish white, or greenish ochroleucous, banner violet-veined; ne Oregon, adjacent Washington.	A. misellus
69. Stipes 0.8–2.5 mm; corollas white or whitish to greenish white, sometimes tinged lilac; California, Idaho, Oregon, Wyoming.	→ 70
70. Flowers 7–9 mm; corollas whitish, sometimes faintly tinged lilac; legumes 10–17 × 2.5–3.5 mm; nc Idaho, w Wyoming.	A. paysonii
70. Flowers 10–16.6 mm; corollas white or greenish white; legumes 14–35 × 2.3–3.6 mm; California, Oregon.	→ 71
71. Legumes 15–35 × 2.3–3.2 mm, stipes 1–2.5 mm; leaflets (11–)17–35(or 37); Sierra Nevada foothills, California.	A. congdonii
71. Legumes 14–24 × 2.6–3.6 mm, stipes 0.8–1.9 mm; leaflets (11–)15–23; outer coast ranges of nw California, w, sw Oregon.	A. umbraticus
68. Legumes straight to incurved, not falcately or lunately so, 7–40(–48) × 2–18(–19) mm; corollas ochroleucous, yellowish, cream, white, or pink-purple; flowers 5.5–23 mm.	→ 72
72. Stems usually shorter than longest inflorescence, with 3–7 developed internodes; corollas ochroleucous, white, or creamy white; legumes erect, unilocular or incompletely bilocular; se Washington, ne Oregon, adjacent Idaho.	A. sheldonii
72. Stems usually longer than longest inflorescence, if shorter then not with 3–7 developed internodes; corollas ochroleucous, yellowish, cream, white, pink-purple; legumes ascending, spreading, reflexed, declined, or pendulous (sometimes humistrate), unilocular to bilocular; Montana to Colorado, west to Washington and California.	→ 73
73. Legumes plumply ovoid, strongly inflated, leathery or stiffly papery, ± bilocular; Tooele County, Utah.	A. lentiginosus
73. Legumes oblong, lanceoloid-ellipsoid, obliquely ovoid, or crescentic, obcompressed, 3-sided, or laterally compressed, fleshy, papery, membranous, leathery, or woody, when obcompressed, then often woody or leathery in age; Montana to Colorado, west to Washington and California.	→ 74
74. Legumes glabrous or strigose.	→ 75
75. Legumes 2.2–3 mm wide, green becoming stramineous; nw Arizona, se Nevada, sw Utah.	A. straturensis
75. Legumes 3–4.5 mm wide, mottled and glaucescent, becoming stramineous and faintly purple-tinged; n Nye County, Nevada.	A. toquimanus
74. Legumes strigulose, strigose, villosulous, hirsutulous, or hirsute.	→ 76
76. Flowers 5.3–6.8 mm; corollas whitish or ochroleucous; legumes 7–12 × 2–3.8 mm; n margin of Snake River Plains, Idaho.	A. oniciformis
76. Flowers (8.6–)10–22 mm; corollas pink-purple, or whitish to ochroleucous, when less than 10 mm, then bright pink-purple and banner veined purple; legumes 12–40 × 3.6–10 mm; California and Oregon east to Colorado and Montana.	→ 77
77. Legumes shaggy-hirsute with lustrous spreading hairs, hairs 1–3 mm.	A. malacus
77. Legumes strigose, hirsutulous, or villosulous, hairs appressed or incumbent, hairs to 1 mm.	→ 78
78. Legumes obcompressed or 3-sided obcompressed, 12–32 × 3.6–10 mm (wider than high in cross section), unilocular or incompletely bilocular, septum 0.6–1 mm wide.	→ 79
79. Legumes 12–16 × 3.6–5 mm, stipes 2–5 mm; Inyo County, California, Lincoln and Nye counties, Nevada.	A. inyoensis
79. Legumes 17–32 × 7–10 mm, stipes to 2 mm; ne Nevada eastward to w Colorado, northward to Idaho and Montana.	A. cibarius
78. Legumes laterally or 3-sided compressed and biconvex, 20–45 × 5–8 mm (cross section at middle narrower or not wider than high), bilocular, septum 3.5–4.2 mm wide.	→ 80
80. Legumes: dorsal sutures prominent, body biconvex, cross section elliptic.	A. malacoides
80. Legumes: dorsal sutures slightly grooved, body 3-sided, cross section deltoid.	A. chamaemeniscus

Key to Species of Group 8

1. Flowers 35–41 mm; corollas scarlet or crimson, banner and keel petals nearly equal length.	A. coccineus
1. Flowers 6–32 mm; corollas pink to pink-purple or lilac, white to ochroleucous, or yellowish, not scarlet or crimson, banners usually longer than keel petals.	→ 2
2. Legumes mostly bilocular (semibilocular in A. eurylobus, unilocular in A. anserinus and A. purshii).	→ 3
3. Plants from deeply subterranean caudex and slender rhizomes; stems single or few; Mojave Desert, Arizona, California, Nevada.	Astragalus layneae
3. Plants from superficial or shallow subterranean caudex, not rhizomatous; stems few to numerous, sometimes reduced to crowns, obsolete, or absent (sometimes single in A. mollissimus); w United States.	→ 4
4. Legumes 3-sided compressed; w Texas to c New Mexico.	→ 5
5. Flowers 18.5–23 mm; calyces 10–14 mm; herbage strigulose; legumes purple-mottled; se New Mexico, w Texas.	A. waterfallii
5. Flowers 13–16 mm; calyces 5.2–8 mm; herbage villous or villosulous; legumes not mottled; c, nc New Mexico.	A. feensis
4. Legumes terete, subterete, dorsiventrally or laterally compressed, or bladdery-inflated (3-sided in A. cottamii, A. holmgreniorum, and A. obscurus); w United States.	→ 6
6. Calyces 3–8 mm; flowers 7–17(–18) mm.	→ 7
7. Legumes bladdery-inflated, ovoid to subglobose, 15–33 × 10–22 mm; elevation 2400–3500 m, montane or subalpine.	A. platytropis
7. Legumes subterete or 3-sided compressed, oblong to lanceoloid or linear, 10–27(–37) × 2–6 mm; elevation 900–2400 m, montane or lower.	→ 8
8. Legumes erect or ascending, straight or slightly incurved, separating from receptacle well after maturity; ne California, n, sw Idaho, n, s Nevada, s, ec Oregon.	→ 9
9. Racemes 7–35-flowered, axis 2.5–14(–25) cm in fruit; legumes 15–26(–30) × 4–6 mm; plants relatively coarse; se California, se to sw Nevada.	A. minthorniae
9. Racemes (3–)6–14-flowered, axis (1–)2–8 cm in fruit; legumes 10–25 × 2.4–3.3 mm; plants slender, delicate; n California, sw Idaho, n Nevada, Oregon.	A. obscurus
8. Legumes ascending or spreading-descending (humistrate), mostly incurved (crescentic), separating from receptacle at maturity; Four Corners region.	→ 10
10. Flowers 7–10.5 mm; calyces 3.6–4.5 mm, tubes 3–3.5(–4.5) mm; Garfield and San Juan counties, Utah.	A. monumentalis
10. Flowers 11–17 mm; calyces 6.2–8 mm, tubes 4.8–6.7 mm; n Navajo County, Arizona, w, sw Montezuma County, Colorado, San Juan County, New Mexico, San Juan County, Utah.	A. cottamii
6. Calyces 9.5–16(–19) mm; flowers 17–25(–26) mm.	→ 11
11. Legumes mostly glabrous; leaflet blades glabrous abaxially or both surfaces hairy.	→ 12
12. Leaflet blades loosely pilose abaxially, glabrous adaxially; plants acaulescent; Virgin River valley, Utah-Arizona border, s of St. George, Mohave County, Arizona, Washington County, Utah.	A. holmgreniorum
12. Leaflet blades hairy, sometimes densely so; plants acaulescent to subacaulescent or short caulescent; Idaho south to Texas.	A. mollissimus
11. Legumes hairy; leaflet blades hairy throughout.	→ 13
13. Legumes shaggy-villous, hairs (2–)2.5–4(–5) mm, often concealing surfaces; California, sc, se Oregon, w Nevada.	A. purshii
13. Legumes glabrous or variously pubescent (villous, pilose, strigulose, puberulent, villosulous, hispidulous, villous-hirsute, -tomentulose, or -tomentose), hairs not concealing surfaces; Idaho south to Texas.	→ 14
14. Legumes sparsely villous, 9–12(–15) × 5–7 mm; flowers 9–11.2 mm; plants dwarf, tuft- or mat-forming, short caulescent; s Cassia County, Idaho, ne Elko County, Nevada, nw Box Elder County, Utah.	A. anserinus
14. Legumes glabrous, strigose, pilose or villous-tomentose, (6–)8–30(–40) × (3–)4–9(–16) mm; flowers 11.8–25 mm; plants usually not dwarf, tuft- or clump-forming, acaulescent, subacaulescent, or short caulescent; Idaho to Texas.	→ 15
15. Legumes 8–10 × 6–8 mm, subterete to slightly obcompressed; Nutrioso, Apache County, Arizona, se of Red Hill, Catron County, New Mexico.	A. nutriosensis
15. Legumes (6–)9–30(–40) × (3–)4–9(–16) mm, inflated, terete, laterally or obcompressed; Nebraska and Texas west to Arizona and Idaho.	→ 16
16. Legumes obliquely oblong- or lanceoloid-ellipsoid, 21–30(–40) × 7.5–9(–16) mm, length 3–4 times width, strigulose; nw Arizona, se Nevada.	A. eurylobus
16. Legumes oblong-ellipsoid, lanceoloid-ellipsoid, ovoid, or ovoid-ellipsoid, (6–)9–24 × (3–)4–13 mm, length 2 times width, glabrous, puberulent, villosulous, hispidulous, villous-hirsute, -tomentulose, or -tomentose; Nebraska to Texas, west to Nevada and Arizona.	A. mollissimus
2. Legumes unilocular.	→ 17
17. Leaflets (1 or)3 or 5.	→ 18
18. Legumes strigulose, hirsutulous, or villous-hirsute, not tomentose.	→ 19
19. Legumes strigulose (hairs appressed, 0.5–0.7 mm), thinly fleshy becoming leathery, valves much less than 1 mm thick; Bonneville Basin, c Nevada, w Utah.	A. uncialis
19. Legumes hirsutulous to villous-hirsute (hairs spreading, 0.6–2 mm), thickly succulent becoming alveolate-spongy (spongy-thickened cellular tissue 1.5–2 mm thick); w Colorado, c, sc Utah.	A. musiniensis
18. Legumes sparsely hirtellous to densely villous-tomentose or villous-hirsute.	→ 20
20. Legumes pilose and tomentulose, hairs concealing surfaces.	A. newberryi
20. Legumes villous-hirsute, hairs not concealing surfaces.	A. eurekensis
17. Leaflets of larger leaves 9–29.	→ 21
21. Herbage silvery-pilose-tomentose; plants subacaulescent, caudex branches obscured by persistent, white leaf bases; Ash Meadows, Nye County, Nevada.	A. phoenix
21. Herbage hirsute, strigose, villous, or pilose, if pilose-tomentose, then not giving a silvery appearance; plants acaulescent, subacaulescent, or short caulescent, caudex branches usually without persistent leaf bases, or if leaf bases persistent then not white; w North America.	→ 22
22. Legumes spreading and ascending in oblong or globose, headlike clusters, plumply ovoid or subglobose, 5–7 × 4–4.5 mm; Coconino Plateau and Mogollon Rim, Coconino County, Arizona.	A. troglodytus
22. Legumes declined to deflexed, ascending to spreading (often humistrate), usually not in clusters, ovoid, ellipsoid, or lanceoloid- to oblong-ellipsoid, 6–50(–55) × 3–18 mm; w North America.	→ 23
23. Legumes papery-membranous, hirsute, hairs lustrous; rimrock habitats.	→ 24
24. Flowers 6–9 mm; n Arizona, wc Colorado, nw New Mexico, se Utah.	A. desperatus
24. Flowers 12–16 mm; near Gateway, Mesa County, Colorado, Uintah County, Utah.	A. equisolensis
23. Legumes leathery, woody, or stiffly papery, if papery, then without lustrous, hirsute hairs; various habitats, including rimrock.	→ 25
25. Legumes strigulose, strigulose-pilosulous, or silky-strigose, hairs appressed or incumbent, 0.4–1 mm.	→ 26
26. Calyx tubes 6.8–11.8 mm; stipules lanceolate, imbricate or not; legumes ovoid, lanceoloid-ellipsoid, oblong-ellipsoid, or ovoid-acuminate, pilosulous, or silky-strigose; not or seldom of rimrock habitats; nw Arizona, e California, nw Colorado, se Idaho, sw Montana, n Nevada, Utah, w Wyoming.	A. argophyllus
26. Calyx tubes 4–6.2 mm; stipules broadly ovate (mostly broader than stem), imbricate; legumes obliquely ellipsoid, 13–22 × 4–6 mm, strigulose; rimrock habitats; wc, sw Colorado, McKinley and San Juan counties, New Mexico, San Juan County, Utah.	A. naturitensis
25. Legumes hirsute, hirsutulous, tomentulose, villous-tomentulose, or tomentose, hairs 1–2.5 mm, or strigose, strigulose, pilosulous, villous, shaggy-villous, or glabrous.	→ 27
27. Plants acaulescent, caudex branches with thatch of persistent stipules and leaf bases.	→ 28
28. Legumes strigose; corollas ochroleucous, sometimes tinged or veined purple, keel tip maculate, wing and keel petals purple-tipped; calyces 10.2–15 mm, cylindric, strigulose, tubes 8.2–11.5 mm, lobes 1.9–3.5 mm, subulate; Henry Mountains, Garfield County, Utah.	A. henrimontanensis
28. Legumes sparsely hirtellous to densely villous-tomentose or villous-hirsute; corollas pink-purple or ochroleucous and suffused with purple; calyces 7–20 mm, cylindric or campanulate, villous or pilose-villous, tubes 5–16 mm, lobes 1–5.7 mm, subulate to lanceolate; w United States.	→ 29
29. Legumes sparsely hirtellous to densely villous-tomentose, hairs usually concealing surface.	A. newberryi
29. Legumes villous-hirsute, surface visible between long, shining hairs.	A. eurekensis
27. Plants acaulescent, subacaulescent, or caulescent to shortly so, caudex branches usually without thatch of persistent leaf bases and stipules, if leaf bases and stipules persistent then not acaulescent.	→ 30
30. Pubescence of leaflets softly villous or tomentose, of fine, cottony, sinuous or entangled hairs, sometimes hirsute-tomentose; legumes initially ascending, in fruit peduncles decumbent and legumes humistrate, villous-tomentose or -tomentulose, shaggy-villous, or hirsute.	→ 31
31. Leaves 1–4 cm; leaflets 5–15, blades 3.2–6.5 mm, obovate, surfaces villous; flowers 9–11.2 mm; corollas pink-purple; nw Utah, ne Nevada, and immediate adjacent Idaho.	A. anserinus
31. Leaves 1–12 cm; leaflets (3–)7–21, blades 2–15(–20) mm, elliptic, rhombic-elliptic, oblanceolate, obovate, oblong-obovate, or suborbiculate, surfaces villous to tomentose or hirsute; flowers (11–)11.5–29(–31) mm; corollas purple, pink-purple, cream, or white; British Columbia south to Utah and California.	→ 32
32. Legumes sparsely or densely villous-tomentulose, hairs to 1 mm; interior s California.	→ 33
33. Leaflets (7–)11–19; raceme axis (0.5–)2–8 cm in fruit; flowers 16–18.5 mm; legumes (13–)15–25 mm, grooved abaxially, bilocular; seeds 18–24; San Antonio, San Bernardino, and Santa Rosa mountains.	A. leucolobus
33. Leaflets 7–11(or 13); raceme axis 0.3–1.6 cm in fruit; flowers (11–)11.5–13.3 mm; legumes 8–15 mm, abaxially flattened proximally, groove slight, unilocular; seeds 11–14; Piute and Sierra Nevada mountains, Kern and Tulare counties.	A. subvestitus
32. Legumes usually densely hirsute or shaggy-villous, sometimes tomentose or villous-hirsute, hairs 1–8 mm; British Columbia south to Utah.	→ 34
34. Flowers (22–)24–29 mm; legumes (25–)30–50 mm; Grapevine Mountains, Inyo County, California, Nye County, Nevada.	A. funereus
34. Flowers 19–31 mm; legumes 7–30 mm; California to British Columbia, east to Colorado, South Dakota and Saskatchewan.	→ 35
35. Legumes lanceoloid-ellipsoid or narrowly ovoid-acuminate, 17–30 × 5.5–7.5 mm, length 3–4 times width, ± straight, shaggy-villous, hairs relatively long, obscuring surfaces; leaflet blades obovate to suborbiculate or ovate; corollas usually pink-purple, rarely white.	A. utahensis
35. Legumes ovoid, ovoid-ellipsoid, or lanceoloid-ellipsoid, 7–26(–30) × 3.5–11(–13) mm, length 2 times width, incurved, shaggy-villous, villous-hirsute, or densely tomentose, hairs short or long, not always concealing surfaces; leaflet blades obovate, elliptic to oblanceolate, or rhombic-elliptic; corollas white, cream, purple, or pink-purple.	A. purshii
30. Pubescence of leaflets straight, appressed or narrowly ascending, or of spreading-incurved and sometimes sinuous or contorted hairs, but not of extremely fine, entangled hairs, never entirely cottony-tomentose, sometimes glabrate; legumes ascending or spreading, strigulose, pilosulous, hirsutulous, hirsute, shaggy-hirsute, silky-strigose, or glabrous.	→ 36
36. Leaflets (7–)17–31 (21+ in at least some leaves).	→ 37
37. Legumes glabrous; calyces sparsely villous-villosulous; sw Colorado, nw New Mexico.	A. iodopetalus
37. Legumes usually strigulose, hirsutulous, or pilosulous, rarely glabrous (if glabrous, then calyces strigulose and plants of Arizona and sw New Mexico); calyces hirsute, strigulose, pilosulous, or villous; Arizona, California east to New Mexico and Wyoming.	→ 38
38. Legumes densely hirsutulous, (20–)25–30 × 6–8 mm; corollas white, veins and keel tips pink; along axis of Rocky Mountains from se Wyoming south to s Colorado.	A. parryi
38. Legumes usually strigulose or pilosulous, rarely glabrous, 13–50 × 5–13 mm; corollas usually pink-purple or dull lilac, rarely white; Arizona, Nevada, New Mexico.	→ 39
39. Legumes 13–30(–34) × 5–10(–12) mm, thinly to thickly fleshy becoming thinly leathery, stiffly leathery, or subligneous, valves less than 1 mm thick; herbage strigulose, pilosulous, or villosulous.	A. tephrodes
39. Legumes 25–50 × 7–13 mm, thickly fleshy becoming woody, valves 1–2 mm thick; herbage strigulose.	A. cyaneus
36. Leaflets 7–21.	→ 40
40. Legumes hirsute or shaggy-hirsute, longest hairs 2–3.5 mm; ec Nevada, c, w Utah.	→ 41
41. Legumes hirsute, hairs relatively long, not concealing surfaces; sandy flats and dunes in valleys and low ranges; c Nevada, wc Utah.	A. callithrix
41. Legumes densely hirsute or shaggy-hirsute, hairs concealing surfaces; montane or cool desert shrub communities; Nevada, Utah.	→ 42
42. Leaflet blades strigose, hairs subappressed and silvery-silky; legumes spreading-ascending, humistrate; keel petals 17–19 mm (2 mm shorter than banners); e Nevada to c, sw Utah.	A. piutensis
42. Leaflet blades strigulose-villosulous, hairs ascending, dull; legumes ascending, not humistrate; keel petals 12–13.3 mm (4.5–9 mm shorter than banners); s Utah County, Utah.	A. desereticus
40. Legumes strigose, strigulose, villosulous, or strigulose-pilosulous, longest hairs less than 1.7 mm; Idaho south to Arizona.	→ 43
43. Legumes laterally compressed at both ends, obcompressed at middle, ± dorsiventrally compressed, (15–)20–55 mm, incurved through 0.5+ spiral, not mottled; herbage villous-hirsute, sometimes also tomentose; Inyo and San Bernardino counties, California, s Clark County, Nevada.	A. tidestromii
43. Legumes dorsiventrally compressed except for laterally compressed beak (if somewhat laterally compressed proximally then shorter and brightly mottled), 15–45 mm, straight or incurved, not spiraling; herbage strigulose, strigose, pilose, or villous-villosulous, not tomentose; Idaho south to Arizona, Nebraska, and Wyoming.	→ 44
44. Legumes (20–)25–45 × (8–)9–18 mm; calyces villous, not silvery, herbage silvery-strigose.	A. shortianus
44. Legumes 15–35(–37) × 5–12(–13) mm; calyces and herbage hairs usually uniform in color.	→ 45
45. Legumes green becoming brown or straw-colored, little or not grooved abaxially; plants mat-forming, caudex not or seldom with persistent leaf bases; Arizona to Idaho, east to Colorado.	A. argophyllus
45. Legumes brightly purple-mottled, grooved abaxially (proximally); plants mat- or tuft-forming, caudex branches sometimes with persistent leaf bases; n Arizona, se Nevada, nw New Mexico, s Utah.	A. zionis

Key to Species of Group 9

1. Legumes broadly ovoid, globose, oblong-ellipsoid or -cylindroid, ± obcompressed, terete, or dorsiventrally or laterally compressed, fleshy, often spongy or succulent, mesocarp 1.5+ mm thick, bilocular; stems usually sprawling or decumbent, sometimes ascending and radiating; sc Canada south to Arizona and Louisiana.	→ 2
2. Legumes strigulose or pilosulous; stems single or few together from widely branching, subterranean, rhizomatous caudex.	A. plattensis
2. Legumes glabrous; stems usually several, clustered from subterranean caudex (not rhizomatous).	→ 3
3. Legumes 15–40 × 12–27 mm (length less than 1.5 times width); stipules glabrous abaxially; leaflet blades glabrous or glabrescent adaxially; sc Canada south to Arizona and Louisiana.	A. crassicarpus
3. Legumes 25–45(–50 × (8–)10–21 mm (length 3–4 times width); stipules strigulose abaxially; leaflet blades cinereous-strigulose; se New Mexico, w Texas.	A. gypsodes
1. Legumes linear-oblong and lanceoloid to cylindroid and oblong-ellipsoid, terete, inflated, or bladdery-inflated, obcompressed, 3-sided, dorsiventrally, or laterally compressed, thin to woody, if fleshy not succulent or spongy (initially succulent in A. pattersonii) and mesocarp less than 1.5 mm thick, unilocular to bilocular; stems erect to prostrate, usually not sprawling (sometimes sprawling in A. ensiformis and A. iselyi); widespread.	→ 4
4. Legumes hirsute, villosulous, villous, tomentose, or tomentulose, longer hairs mostly 1+ mm.	→ 5
5. Legumes bilocular.	→ 6
6. Legumes 11–38 mm.	→ 7
7. Legumes erect to ascending, subterete or somewhat laterally compressed, not grooved abaxially; s Nevada south and west to se California.	A. minthorniae
7. Legumes reflexed or declined, 3-sided compressed, grooved abaxially; California, Idaho, Oregon, Nevada.	→ 8
8. Legumes 11–15 × 3–3.4 mm; flowers 9.1–11 mm.	A. agnicidus
8. Legumes 18–38 × 4.5–6 mm; flowers 12–15 mm.	A. malacus
6. Legumes (3.5–)4–8 mm.	→ 9
9. Calyx tubes narrowly campanulate or turbinate, 1.6–2.5 × 1.8–2.6 mm, not accrescent, covering less than 1/2 of mature legumes; Kittitas to Douglas and Franklin counties, Washington.	A. lyallii
9. Calyx tubes broadly campanulate, (2.5–)3.1–4.5 × (2.4–)2.6–4.1 mm, somewhat accrescent, covering most or all of mature legume; Idaho, Oregon, Washington.	→ 10
10. Corollas whitish, often tinged lavender, glabrous abaxially; leaflet blades villous or villous-pilose; wc Idaho, Blue Mountains, ne Oregon, c, se Washington, sc British Columbia.	A. spaldingii
10. Corollas pale yellow, pubescent abaxially; leaflet blades densely villous-tomentose; Wasco County, Oregon.	A. tyghensis
5. Legumes unilocular.	→ 11
11. Flowers 8.3–11.4 mm; corollas pale or greenish yellow; legumes bladdery-inflated, 20–40 × 14–20 mm; leaflets (11–)17–27(or 29); racemes (8–)10–30(–35)-flowered; Inner Coast Ranges, San Benito and Monterey to San Luis Obispo and Santa Barbara counties, California.	A. macrodon
11. Flowers (6.3–)8.2–25.5 mm; corollas pink-purple; legumes obcompressed, 13–40(–45) × (5–)7–13 mm; leaflets (7–)11–23(–27); racemes (2 or)3–18-flowered; Washington and Montana, south to Utah.	→ 12
12. Flowers (16.5–)19–25.5 mm; legumes fleshy becoming stiffly leathery.	→ 13
13. Leaflets (7–)11–17; racemes (2–)4–8-flowered; legumes sparsely villous-hirsute, not tomentose; Owyhee Desert, sw Idaho, ec Oregon.	A. nudisiliquus
13. Leaflets (9–)17–23(–27); racemes (5–)8–18-flowered; legumes villous-hirsute or tomentose; w Montana, across n Idaho to sc Washington, ne Oregon.	A. inflexus
12. Flowers 5.2–8.2 mm; legumes thin becoming papery or papery-membranous.	→ 14
14. Legumes papery-membranous, hirsute, hairs lustrous; rimrock habitats.	→ 15
15. Flowers 6–9 mm; n Arizona, wc Colorado, nw New Mexico, se Utah.	A. desperatus
15. Flowers 12–16 mm; near Gateway, Mesa County, Colorado, Uintah County, Utah.	A. equisolensis
14. Legumes leathery, woody, or stiffly papery, if papery, then not hirsute with lustrous hairs; various habitats, including rimrock.	→ 16
16. Legumes strigulose, strigulose-pilosulous, or silky-strigose (hairs appressed or incumbent, 0.4–1 mm).	→ 17
17. Calyx tubes 6.8–11.8 mm; stipules lanceolate, imbricate or not; legumes ovoid, lanceoloid-ellipsoid, oblong-ellipsoid, or ovoid-acuminate, 15–32(–37) × 5–12(–13) mm (often proportionately broader), strigulose, strigulose-pilosulous, or silky-strigose; seldom of rimrock habitats; nw Arizona, e California, nw Colorado, se Idaho, sw Montana, n Nevada, Utah, w Wyoming.	A. argophyllus
17. Calyx tubes 4–6.2 mm; stipules broadly ovate (mostly broader than stem), imbricate; legumes obliquely ellipsoid, 13–22 × 4–6 mm, strigulose; rimrock habitats; wc, sw Colorado, McKinley and San Juan counties, New Mexico, San Juan County, Utah.	A. naturitensis
16. Legumes hirsute, hirsutulous, tomentulose, villous-tomentulose, or tomentose (hairs 1–2.5 mm), or strigose, strigulose, pilosulous, villous, shaggy-villous, or glabrous.	→ 18
18. Plants acaulescent, caudex branches with thatch of persistent stipules and leaf bases.	→ 19
19. Legumes strigose; corollas ochroleucous, sometimes tinged or veined purple, keel tip maculate, wing and keel petals purple-tipped; calyces 10.2–15 mm, cylindric, strigulose, tubes 8.2–11.5 mm, lobes 1.9–3.5 mm, subulate; Henry Mountains, Garfield County, Utah.	A. henrimontanensis
19. Legumes sparsely hirtellous to densely villous-tomentose or villous-hirsute; corollas pink-purple or ochroleucous and suffused with purple; calyces 7–20 mm, cylindric or campanulate, villous or pilose-villous, tubes 5–16 mm, lobes 1–5.7 mm, subulate to lanceolate; w United States.	→ 20
20. Legumes sparsely hirtellous to densely villous-tomentose, hairs usually concealing surfaces.	A. newberryi
20. Legumes villous-hirsute, surface visible between long, shining, hairs, hairs not concealing surfaces.	A. eurekensis
18. Plants acaulescent, subacaulescent, or caulescent to shortly so, caudex branches usually without thatch of persistent leaf bases and stipules, if leaf bases and stipules persistent then not acaulescent.	→ 21
21. Pubescence of leaflets softly villous or tomentose, of fine, cottony, sinuous or entangled hairs, sometimes hirsute-tomentose; legumes initially ascending, in fruit peduncles decumbent and legumes humistrate, villous-tomentose or -tomentulose, shaggy-villous, or hirsute.	→ 22
22. Leaves 1–4 cm; leaflets 5–15, blades 3.2–6.5 mm, obovate, surfaces villous; flowers 9–11.2 mm; corollas pink-purple; nw Utah, ne Nevada, and adjacent Idaho.	A. anserinus
22. Leaves 1–12 cm; leaflets (3–)7–21, blades 2–15(–20) mm, elliptic, rhombic-elliptic, oblanceolate, obovate, oblong-obovate, or suborbiculate, surfaces villous to tomentose or hirsute; flowers (11–)11.5–29(–31) mm; corollas purple, pink-purple, cream, or white; British Columbia south to Utah.	→ 23
23. Legumes sparsely or densely villous-tomentulose, hairs to 1 mm; interior s California.	→ 24
24. Leaflets (7–)11–19; raceme axis (0.5–)2–8 cm in fruit; flowers 16–18.5 mm; legumes (13–)15–25 mm, grooved abaxially, bilocular; seeds 18–24; San Antonio, San Bernardino, and Santa Rosa mountains.	A. leucolobus
24. Leaflets 7–11(or 13); raceme axis 0.3–1.6 cm in fruit; flowers (11–)11.5–13.3 mm; legumes 8–15 mm, abaxially flattened proximally, groove slight, unilocular; seeds 11–14; Piute and Sierra Nevada mountains, Kern and Tulare counties.	A. subvestitus
23. Legumes usually densely hirsute or shaggy-villous, sometimes tomentose or villous-hirsute, hairs 1–8 mm; British Columbia south to Utah.	→ 25
25. Flowers (22–)24–29 mm; legumes (25–)30–50 mm; Grapevine Mountains, Inyo County, California, Nye County, Nevada.	A. funereus
25. Flowers 19–31 mm; legumes 7–30 mm; California to British Columbia, east to Colorado, South Dakota and Saskatchewan.	→ 26
26. Legumes lanceoloid-ellipsoid or narrowly ovoid-acuminate, 17–30 × 5.5–7.5 mm, length 3–4 times width, ± straight, shaggy-villous, hairs relatively long, obscuring surfaces; leaflet blades obovate, suborbiculate, or ovate; corollas usually pink-purple, rarely white.	A. utahensis
26. Legumes ovoid, ovoid-ellipsoid, or lanceoloid-ellipsoid, 7–26(–30) × 3.5–11(–13) mm, length 2 times width, incurved, shaggy-villous, villous-hirsute, or densely tomentose hairs short or long, not always concealing surfaces; leaflet blades obovate, oblanceolate, elliptic, or rhombic-elliptic; corollas white, cream, purple, or pink-purple.	A. purshii
21. Pubescence of leaflets straight, appressed or narrowly ascending, or of spreading-incurved and sometimes sinuous or contorted hairs, but not of extremely fine, entangled hairs, never entirely cottony-tomentose, sometimes glabrate; legumes ascending or spreading, strigulose, pilosulous, hirsutulous, hirsute, shaggy-hirsute, silky-strigose, or glabrous.	→ 27
27. Legumes glabrous; calyces sparsely villous-villosulous; sw Colorado, nw New Mexico.	A. iodopetalus
27. Legumes usually strigulose, hirsutulous, or pilosulous, rarely glabrous (when legumes glabrous, then calyces strigulose and plants of Arizona and sw New Mexico); calyces hirsute, strigulose, pilosulous, or villous; California east to New Mexico and Wyoming.	→ 28
28. Legumes densely hirsutulous, (20–)25–30 × 6–8 mm; corollas white, veins and keel tips pink; along axis of Rocky Mountains from se Wyoming south to s Colorado.	A. parryi
28. Legumes usually strigulose or pilosulous, rarely glabrous, 13–50 × 5–13 mm; corollas usually pink-purple or dull lilac, rarely white; Arizona, Nevada, New Mexico.	→ 29
29. Legumes 13–30(–34) × 5–10(–12) mm, thinly to thickly fleshy becoming thinly leathery, stiffly leathery, or subligneous, valves less than 1 mm thick; herbage strigulose, pilosulous, or villosulous.	A. tephrodes
29. Legumes 25–50 × 7–13 mm, thickly fleshy becoming woody, valves 1–2 mm thick; herbage strigulose.	A. cyaneus
4. Legumes often glabrous, if pubescent then strigulose, strigose, pilose, villous, hirsutulous, or villosulous, hairs to 1 mm.	→ 30
30. Legumes deflexed, 4.5–12 × 1.3–2.3 mm, bilocular or sub-bilocular; flowers 4.2–6.2 mm.	→ 31
31. Legumes strigulose, 6–12 mm; sw New Mexico.	A. vaccarum
31. Legumes glabrous, 4.5–7 mm; California inner coast ranges.	A. clevelandii
30. Legumes erect, spreading, ascending, declined, deflexed, or pendulous, (4–)8–48(–55) × (1.5–)3–20(–24) mm, unilocular to bilocular; flowers (4.6–)5–34 mm.	→ 32
32. Legumes mostly pendulous, sometimes ascending, spreading, or loosely declined, 2.3–5.5 mm wide, straight or slightly decurved (except incurved in A. sparsiflorus); plants from superficial caudex (sometimes slightly subterranean in A. robbinsii).	→ 33
33. Legumes obtusely 3-sided; seeds 6–10; plants mesophytic; n Utah north to Alaska, east to Newfoundland and New England.	A. robbinsii
33. Legumes dorsiventrally, laterally, or ± 3-sided compressed; seeds (6–)10–29; plants xerophytic; California and Oregon east to Colorado and New Mexico.	→ 34
34. Legumes ± 3-sided compressed; racemes (1 or) 2–10-flowered; flowers 5.5–8 mm; upper Platte and Upper Arkansas drainages, montane Colorado.	A. sparsiflorus
34. Legumes mostly dorsiventrally compressed (sometimes laterally compressed in A. atratus); racemes 1–18-flowered; flowers 4–13.4 mm; California and Oregon east to Colorado and New Mexico.	→ 35
35. Racemes all alike, (2–)5–18-flowered; keel petals 6–10 mm; Great Basin and Owyhee deserts.	A. atratus
35. Racemes of 2 types: early ones subradical, shorter than leaves, 1(or 2)-flowered, later ones cauline, much surpassing leaves, 2–5(–7)-flowered; keel petals 3.5–4.5 mm; Arizona, Colorado, New Mexico, Utah.	A. brandegeei
32. Legumes erect, ascending, spreading, declined, deflexed or pendulous, (2–)4–32 mm wide, straight or slightly to strongly incurved (sometimes decurved in A. panamintensis); plants from superficial or subterranean caudex.	→ 36
36. Plants annual or biennial; legumes deflexed or declined, lunately incurved.	A. diaphanus
36. Plants perennial, or sometimes annual or biennial; legumes erect, spreading, ascending, declined, deflexed, or pendulous, not lunately incurved (except A. diaphanus).	→ 37
37. Legumes erect, obliquely ovoid or ovoid-ellipsoid, 8–18 mm wide; flowers 11.6–15 mm; corollas whitish to pale yellow (drying ochroleucous); New York to Manitoba south to Ohio and South Dakota.	A. neglectus
37. Legumes erect, spreading, ascending, declined, deflexed, or pendulous, if erect then not obliquely ovoid or ovoid-ellipsoid, (2–)4–32 mm wide; flowers (4.6–)5–34 mm; corollas white, ochroleucous, greenish yellow or pink-purple; widespread.	→ 38
38. Legumes erect to incurved-ascending.	→ 39
39. Banner petal crinkled apically, 10.5–14 mm, wings 12.8–17 mm (longer than banner); calyces (6.9–)7.6–10.6 mm, lobes (1.9–)2.2–5.2 mm; Nes Perce County, Idaho, Asotin, Columbia, and Whitman counties, Washington.	A. riparius
39. Banner petal smooth apically, (13.5–)14–24(–25.3) mm, wings (12.4–)13.5–23.7 mm (usually shorter than banner); calyces (5.7–)6–14.8 mm, lobes 1–6.5 mm; w and se United States including Washington and Idaho.	→ 40
40. Stipules herbaceous; legumes (20–)25–40 × (4–)5–7(–8) mm, 3-sided; c to se Washington, adjacent Oregon.	A. succumbens
40. Stipules mostly papery to membranous (herbaceous in A. giganteus, herbaceous distally in A. michauxii); legumes 13–31 × 4–13 mm, subterete, dorsiventrally, or obcompressed (sometimes turgid); w, se United States including Oregon and Washington.	→ 41
41. Stems with 2–5(–7) developed internodes, shorter than combined length of peduncles and racemes (sometimes longer in A. sheldonii); legumes glabrous or strigulose; Idaho County, Idaho, to ne Oregon and adjacent Washington.	→ 42
42. Legumes glabrous, obliquely ovoid-acuminate to broadly lanceoloid- or oblong-ellipsoid, 7–10 mm wide, ± not grooved abaxially, ± unilocular, septum 0–0.9 mm wide; Blue Mountains in ne Oregon, adjacent se Washington, Ada County, Idaho.	A. reventus
42. Legumes usually strigulose, rarely glabrous, narrowly oblong-ellipsoid, (4–)4.5–6.3 mm wide, grooved abaxially, semibilocular, septum 1–1.6 mm wide; Lewis and Nez Perce counties, Idaho, Wallowa County, Oregon, Asotin County Washington.	A. sheldonii
41. Stems with 5–10 well-developed internodes, longer than combined length of peduncles and racemes; legumes glabrous; sw, se United States.	→ 43
43. Herbage pilose and tomentulose; calyces (7.8–)10–14.7 mm; sc New Mexico, w Texas.	A. giganteus
43. Herbage strigulose-pilosulous; calyces (5.7–)6–10.3 mm; se United States and Idaho.	→ 44
44. Legumes 13–18 mm, unilocular; racemes (4–)7–22-flowered; s Idaho, s from Boise and Custer counties.	A. adanus
44. Legumes 23–31 mm, sub-bilocular; racemes (12–)15–40-flowered; Atlantic Coastal Plain and Piedmont, se North Carolina south to se Georgia.	A. michauxii
38. Legumes usually spreading, spreading-ascending (humistrate), or declined to pendulous, sometimes erect or erect-ascending.	→ 45
45. Stems prostrate; leaflet blades 2–11 mm, microphyllous; flowers 4.8–6.1 mm; legumes 4–7 mm; peduncles often 2 or 3 per node; seeds 2–8; California, Nevada, Oregon borders.	→ 46
46. Herbage gray-pilosulous; leaflets 7 or 9, blades folded, apex emarginate; legumes lunately ellipsoid-obovoid, somewhat depressed but not grooved abaxially, laterally compressed, lateral faces with shallow longitudinal groove, unilocular; seeds 2 or 3; arid ash deposits; c Washoe County, Nevada.	A. tiehmii
46. Herbage villous-tomentose; leaflets (7 or)9–15, blades flat or loosely folded, apex obtuse to subacute; legumes ellipsoid or oblong-ellipsoid, 3-sided compressed, bilocular; seeds 4–8; stream banks and saline meadows; California, Nevada, Oregon.	A. lemmonii
45. Stems erect, ascending, spreading, decumbent, reclining, or prostrate; leaflet blades 1–33(–50) mm, usually with at least some blades more than 11 mm; flowers 4.6–34 mm; legumes 6–55 mm; peduncles 1 per node; seeds 6–75(–84); widespread.	→ 47
47. Legumes mostly ± bilocular, septum usually 1+ mm wide (unilocular in A. columbianus, sometimes unilocular in A. iodanthus, A. serenoi, ± unilocular in A. neomexicanus, subunilocular in A. praelongus).	→ 48
48. Racemes 1–4(–6)-flowered; flowers ascending at anthesis; flowers 8.2–14 mm; legumes 8–18 × (2.3–)3.4–4.7 mm, bluntly 3-sided; plants tuft- or mat-forming; leaflet blades linear-elliptic or subulate; Inyo County, California.	A. panamintensis
48. Racemes (2–)5–35(–45)-flowered; flowers usually ascending, spreading, or declined, rarely deflexed; flowers 5.5–26(–27) mm; legumes (7–)9–45(–48) × (2–)2.4–12(–25) mm, inflated, subterete, obcompressed, 3-sided, laterally, or dorsiventrally compressed; plants not tuft- or mat-forming, sometimes clump-forming; leaflet blades usually linear to elliptic or broader, rarely filiform; w North America.	→ 49
49. Racemes subcapitate, loosely 2–10-flowered, flowers ascending, axis to 1 cm in fruit; flowers (17–)18.1–19.5(–20) mm; corollas whitish, keel petals maculate; legumes humistrate, 25–40 × 8.5–10.5 mm; Benton and Yakima counties, Washington.	A. columbianus
49. Racemes not subcapitate, (2 or)3–35(–48)-flowered, rarely loosely so, flowers straight, erect, or incurved-ascending, axis (0.3–)2–20(–26) cm in fruit; flowers 5.5–26(–27) mm; corollas usually pink-purple, ochroleucous, greenish purple, pale lemon yellow, or whitish, rarely cream, keel petals maculate or not; legumes humistrate or not, (7–)10–45(–48) × (2–)2.4–18(–19) mm; w North America.	→ 50
50. Racemes 5–12-flowered; flowers spreading to declined; legumes ascending to spreading, moderately inflated, ellipsoid or ovoid-ellipsoid, 15–17 × 7–8 mm; Butte and Custer counties, Idaho.	A. amnis-amissi
50. Racemes (2 or)3–35(–48)-flowered; flowers erect, ascending, spreading, declined, or deflexed; legumes erect, ascending, descending, deflexed, declined, or pendulous, inflated, obcompressed, subterete, 3-sided, laterally, or dorsiventrally compressed, linear to subglobose or crescentic including ellipsoid and ovoid, 7–45(–48) × 2–25 mm; w North America.	→ 51
51. Flowers nodding, secund and retrorsely imbricate; corollas dull pinkish lavender, greenish purple, or bright magenta-purple; Lincoln and Otero counties, New Mexico.	A. neomexicanus
51. Flowers ascending, spreading, erect, declined, or deflexed, when secund, retrorsely imbricate, then corolla not dull pinkish lavender, green-purple or magenta-purple; w North America.	→ 52
52. Legumes readily disjointing from receptacle.	→ 53
53. Legumes 7–9 × 2–2.5 mm, narrowly lanceoloid; flowers 7.5–8 mm; corollas pink-purple or bluish lavender; Cochise and Santa Cruz counties, Arizona.	A. hypoxylus
53. Legumes 8–40(–48) × (2.5–)3–18(–19) mm, linear to subglobose (including lanceoloid); flowers 5.5–23 mm; corollas pink-purple, yellowish, or whitish; w North America.	→ 54
54. Legumes inflated or swollen (ovoid to globose), ± bilocular.	A. lentiginosus
54. Legumes scarcely inflated or dorsiventrally or laterally compressed, unilocular to bilocular.	→ 55
55. Legumes 3-sided or subterete, bilocular.	A. lentiginosus
55. Legumes 3-sided or dorsiventrally compressed, semibilocular or unilocular.	→ 56
56. Plants from superficial caudex; herbage strigulose or glabrate, exceptionally villosulous, hairs to 0.3–0.7 mm; sagebrush or pinyon-juniper communities, not of dunes; California, Idaho, Nevada, Oregon, Utah.	A. iodanthus
56. Plants from shallow to deep subterranean caudex; herbage villosulous or villous, hairs to 0.7–1.2 mm; dunes and pumice sands; c, wc Nevada, adjacent California.	A. pseudiodanthus
52. Legumes firmly attached to the receptacle, falling while still attached to pedicel.	→ 57
57. Leaflets (1–)5–13; w, nw Great Basin.	→ 58
58. Legumes linear-oblong, straight, 2.4–3.3 mm wide, thinly fleshy becoming leathery; plants slender, wiry.	A. obscurus
58. Legumes plumply oblong, straight or slightly incurved, 5–12 mm wide, fleshy becoming woody; plants robust.	A. serenoi
57. Leaflets (3–)11–33; w North America.	→ 59
59. Plants from subterranean caudex; stems usually ± decumbent, rarely ascending; legumes humistrate, 3-sided, subterete, or laterally compressed; plants not selenophytes.	→ 60
60. Legumes: abaxial suture slightly grooved, body 3-sided, cross section deltoid.	A. chamaemeniscus
60. Legumes: abaxial suture forming a prominent ridge, body sides biconvex, cross section elliptic.	→ 61
61. Leaflet blades usually strigose, sometimes glabrous adaxially; flowers (11–)13–17 mm; Mohave County, Arizona, Lincoln County, Nevada, Washington County, Utah.	A. ensiformis
61. Leaflet blades hirtellous abaxially, glabrous adaxially; flowers 16–22 mm; Kane and Wayne counties, Utah.	A. malacoides
59. Plants from superficial caudex; stems erect to ascending; legumes erect-ascending or spreading, sometimes deflexed or declined, not humistrate, obcompressed, inflated, or subterete, sides not biconvex; when legumes declined or deflexed, then plants selenophytes.	→ 62
62. Legumes deflexed or declined; corollas purple, with white or pale wing tips; Cameron, Coconino County, Arizona.	A. beathii
62. Legumes erect, spreading, ascending, or declined; corollas whitish, yellowish or pink-purple; w North America.	→ 63
63. Legumes ellipsoid, ovoid, cylindroid, obovoid, or subglobose, 5–25 mm wide, subunilocular (septum 0.8–2.3 mm wide); flowers deflexed; corollas usually ochroleucous, sometimes lemon yellow; plants selenophytes.	A. praelongus
63. Legumes narrowly oblong or oblong-ellipsoid, 4–6.5 mm wide, ± bilocular; flowers ascending, spreading, or declined; corollas ochroleucous with dull purple keel tips or pink-purple with pale or white wing tips; plants not selenophytes.	→ 64
64. Legumes subsessile or substipitate (contracted at base into short neck, stipes to 1.5 mm), subterete (compressed laterally when pressed); Lincoln, Nye, and White Pine counties, Nevada.	A. minthorniae
64. Legumes sessile (rounded or, sometimes, with short, thick neck at base), not or slightly inflated (slightly turgid); Mohave County, Arizona, Clark County, Nevada, Washington County, Utah.	A. lentiginosus
47. Legumes ± unilocular, septum, when present, usually less than 1 mm wide (A. serenoi septum 2–4 mm).	→ 65
65. Legumes bladdery-inflated, (5–)6–45(–60) × (1.4–)5–20(–32) mm, terete, obcompressed, or dorsiventrally compressed (scarcely inflated in A. sparsiflorus and A. diaphanus).	→ 66
66. Plants from subterranean or superficial caudex; leaflets 9–15, or 25–41 and stems fistulose.	→ 67
67. Stems underground for (0–)1–4 cm, not fistulose; leaflets 9–15; Spring (Charleston) Mountains, Clark County, Nevada.	A. aequalis
67. Stems aboveground, fistulose; leaflets 25–41; San Luis Obispo and Santa Barbara counties, California.	A. pomonensis
66. Plants from superficial caudex; leaflets (3–)7–29(–35), if stems fistulose, then leaflets (17 or)19–35.	→ 68
68. Legumes unilocular or subunilocular, partial septum 0.5–1 mm wide.	→ 69
69. Leaflets (19 or)21–29; racemes (13–)18–25-flowered; San Diego County, California.	A. deanei
69. Leaflets (5 or)7–21; racemes (1 or)2–15-flowered; Colorado, New Mexico, Oregon, Washington.	→ 70
70. Herbage villosulous; seeds 18–22.	A. cerussatus
70. Herbage strigulose; seeds 6–15.	→ 71
71. Legumes papery, not translucent; Colorado.	A. sparsiflorus
71. Legumes papery-membranous, becoming translucent; e Oregon (formerly sc Washington).	A. diaphanus
68. Legumes unilocular, without any septum.	→ 72
72. Racemes (1 or)2–10(–15)-flowered.	→ 73
73. Calyces 6.7–7.8 mm, tube 3.7–3.9 mm; flowers 9.5–11 mm; corollas greenish white, often tinged or veined dull lilac; legumes 25–40 mm; lower Lemhi and upper Salmon rivers, Idaho.	A. aquilonius
73. Calyces 3.4–6.4 mm, tube 1.7–3(–3.2) mm; flowers 4.6–7.5 mm; corollas pink-purple, pale lilac or whitish with lilac tips or tinged pink or lavender; legumes 10–37(–43) mm; Colorado and Texas west to California southward.	→ 74
74. Legumes strigulose with straight hairs.	A. wootonii
74. Legumes loosely strigulose or strigulose-villosulous, hairs spreading, incumbent or curly.	→ 75
75. Leaflets 13–21; seeds 18–26.	A. cerussatus
75. Leaflets (7 or)9–15(or 17); seeds 10–14.	A. gilmanii
72. Racemes (7–)10–60(–75)-flowered.	→ 76
76. Plants silvery- or satiny-strigulose; desert dunes.	A. magdalenae
76. Plants villosulous, strigulose, glabrate, or glabrous, green, cinereous, or silvery, when silvery then not of desert dunes.	→ 77
77. Herbage and legumes villosulous or strigulose-villosulous; s Coast Ranges, California.	A. macrodon
77. Herbage and legumes mostly strigulose, sometimes villosulous or glabrous; California to Texas.	→ 78
78. Legumes 6–13 × 6–10 mm, broadly and plumply ovoid- or obovoid-ellipsoid, obovoid, or subglobose, beak almost obsolete; s Arizona, sw New Mexico.	A. thurberi
78. Legumes 9–40(–60) × (4–)5–20(–32) mm, when shorter than 15 mm then strongly beaked, ovoid to ellipsoid or subglobose; California to Texas.	→ 79
79. Racemes (15–)20–60(–75)-flowered; corollas ochroleucous, rarely tinged purple, drying brownish; leaflets (17 or)19–35; legumes stiffly papery; San Diego County, California.	A. oocarpus
79. Racemes 5–30(–40)-flowered; corollas whitish, yellowish, or pink-purple; leaflets (7–)11–29, when leaflets more than 21 then legumes thinly papery; California to Texas.	→ 80
80. Legumes subsymmetrically ovoid-ellipsoid or subglobose, beak poorly developed; plants winter annuals or biennials.	A. wootonii
80. Legumes obliquely ovoid, ovoid-ellipsoid, ovoid-acuminate, or ellipsoid, beak strongly developed; plants usually perennials (A. allochrous sometimes biennial).	→ 81
81. Corollas pink-purple; Arizona, California, New Mexico, Texas.	→ 82
82. Legumes 9–23 mm.	A. palmeri
82. Legumes (20–)25–40(–45) mm.	A. allochrous
81. Corollas ochroleucous, or greenish white, rarely tinged with purple; cismontane California south to edge of s Mojave and Colorado deserts.	→ 83
83. Legumes 25–60 mm; seeds 42–71; banners (6.4–)7.8–13 mm.	A. douglasii
83. Legumes 9–28 mm; seeds (7–)12–40; banners 12–15 mm or 7–10.3 mm.	→ 84
84. Leaflets (19 or)21–29; banners 12–15 mm; keel petals 8–10.5 mm.	A. deanei
84. Leaflets (9 or)11–21; banners 7–10.3 mm; keel petals 6.2–8.8 mm.	A. palmeri
65. Legumes mostly not bladdery-inflated, (7–)9–55 × (2.8–)5–20(–24) mm, when bladdery, then 7–29 × 4.5–17(–18) mm, terete, subterete, obcompressed, 3-sided, or dorsiventrally compressed.	→ 85
85. Legumes pendulous, strongly incurved or coiled, fleshy becoming stiffly papery, sharply 4-angled; se Oregon to sw Utah and adjacent Arizona.	A. tetrapterus
85. Legumes erect, ascending, spreading, horizontal, declined, deflexed, or pendulous, usually straight or slightly incurved, sometimes falcate, sigmoid-arcuate, or coiled, rarely decurved, fleshy, papery, leathery, or woody, inflated, terete, subterete, obcompressed, 3-sided, or dorsiventrally compressed; w United States.	→ 86
86. Leaflets (1 or)3–13, blades 6–35(–50) mm, apex mucronate or acute to mucronate; plants selenophytes; Grand and San Juan counties, Utah.	→ 87
87. Flowers 23–34 mm; calyx tubes 11–14 mm; Mancos Shale and Morrison formations, near Cisco and nw of Moab, Grand County, Utah.	A. sabulosus
87. Flowers 17–19 mm; calyx tubes 5.5–6.3 mm; Morrison and Paradox formations, foothills of La Sal Mountains, Grand and San Juan counties, Utah.	A. iselyi
86. Leaflets (1–)5–27(–33), blades 1.5–30(–50) mm, apex acute to emarginate and mucronate; plants not selenophytes (except A. pattersonii, A. praelongus, and A. preussii); w United States including Utah.	→ 88
88. Plants 3–11 cm, humifusely mat-forming, densely gray-villous; tuffaceous sands; s Idaho, ne Nevada, nw Utah.	A. anserinus
88. Plants 1.5–60(–120) cm, not mat-forming, usually strigulose, villosulous, or pilosulous, rarely glabrous; canyon slopes, volcanic tuff, igneous, granite, or basaltic soils, grassland, sagebrush, and desert communities, pinyon-juniper communities, woodlands, rarely seleniferous soils; w United States.	→ 89
89. Legumes obliquely ovoid, ovoid-ellipsoid, or lanceoloid-ellipsoid, inflated or bladdery-inflated, deciduous from receptacle, papery or papery-membranous; axis of raceme 0.2–5 cm in fruit.	→ 90
90. Plants 1.5–13(–25) cm, not tuft- or clump-forming.	→ 91
91. Leaflets (7 or)9–15(or 17), blades 5–12.5 mm; legumes 13–26 × 8–16 mm; se California, Lincoln County, Nevada.	A. gilmanii
91. Leaflets (3 or)5–9, blades 1.5–7 mm; legumes 7–14 × 4.5–7.5 mm; Pahute Mesa, sc Nye County, Nevada.	A. beatleyae
90. Plants (3–)8–50 cm, mostly tuft- or clump-forming (except A. wardii).	→ 92
92. Flowers 5–8 mm; plants tuft-forming or not; legumes bladdery-inflated, often purple-mottled; high plateaus of sc Utah, disjunct in e Great Basin.	→ 93
93. Leaflets (11–)15–23, blades mostly glabrescent or glabrous; racemes loosely flowered, axis 1–5 cm in fruit; legumes glabrous.	A. wardii
93. Leaflets 9–15, blade surfaces strigose-pilosulous; racemes subumbellate, axis 0.2–1 cm in fruit; legumes strigose.	A. serpens
92. Flowers 8.8–12.2 mm and plants tuft-forming, or 6.3–8.2 mm and plants clump-forming; legumes inflated, not strongly bladdery, red- or purple-mottled or not mottled; Colorado, Utah, Wyoming.	→ 94
94. Legumes strongly incurved, thin becoming papery, shaggy-pilose, hairs lustrous, 1–2 mm; seeds 9–18.	A. pubentissimus
94. Legumes slightly incurved, firmly papery, villosulous, hairs incurved, to 0.7 mm; seeds 20–28.	A. pardalinus
89. Legumes either narrower than ovoid or persistent on receptacle, papery to woody, if fleshy then becoming leathery or woody, not bladdery-inflated or if swollen then racemes 6–20 cm.	→ 95
95. Plants from subterranean caudex; legumes pendulous, deflexed, or spreading-declined.	→ 96
96. Legumes fleshy, obcompressed, 20–55 × (5–)6–10 mm; nw, w Nevada, adjacent California.	A. casei
96. Legumes papery, terete, dorsiventrally compressed, or 3-sided, 13–34 × 2.8–5 mm; Arizona, Colorado, Utah.	→ 97
97. Legumes 3-sided; stems prostrate to decumbent-ascending; Montezuma County, Colorado, San Juan County, Utah.	A. cronquistii
97. Legumes terete or dorsiventrally compressed; stems erect; n Arizona.	A. atwoodii
95. Plants from superficial caudex (sometimes shallowly subterranean in A. praelongus); legumes ascending, spreading, declined, or erect.	→ 98
98. Stems decumbent to ascending (diffuse); peduncles spreading-ascending; legumes ascending and humistrate; ne Nevada eastward to w Colorado, northward to Idaho and Montana.	A. cibarius
98. Stems mostly ascending to erect, sometimes decumbent or reclining; peduncles mostly erect or erect-ascending (A. pinonis divaricate or widely incurved-ascending); legumes erect, spreading, ascending, or declined, not humistrate; Arizona, California, Colorado, Idaho, Nevada, New Mexico, Texas, Utah.	→ 99
99. Leaflets (1–)5–11, blades linear, linear-oblanceolate, or filiform, surfaces silvery-canescent adaxially; c, w Nevada, adjacent California.	A. serenoi
99. Leaflets (5–)9–33, blades linear, oblong, lanceolate, elliptic, oblanceolate, obovate, obcordate or suborbiculate, surfaces mostly glabrous adaxially, not silvery or canescent; Arizona, California, Colorado, Idaho, Nevada, New Mexico, Texas, Utah.	→ 100
100. Legumes 20–35 × 5.5–8 mm, terete or subterete; corollas greenish to ochroleucous, suffused with purple; usually growing upward through low sagebrush.	A. pinonis
100. Legumes 12–42 × 4–25 mm, subterete, obcompressed, dorsiventrally compressed, or inflated; corollas ochroleucous, white to pale greenish yellow, pale lemon yellow, or pink-purple; seldom growing upward through low sagebrush.	→ 101
101. Legumes 13–18 × 4–6 mm, subligneous in age; plants not selenophytes.	A. adanus
101. Legumes 12–42 × 5–25 mm, stiffly papery to leathery or leathery-woody in age; plants selenophytes.	→ 102
102. Corollas pink-purple; legumes stiffly papery to leathery, unilocular.	A. preussii
102. Corollas ochroleucous, white, or pale lemon yellow, keel petals sometimes with purple tips; legumes fleshy becoming leathery-woody, or succulent becoming stiffly leathery, unilocular or subunilocular (septum 0–2.3 mm wide).	→ 103
103. Corollas ochroleucous or pale lemon yellow, keel petals with maculate (purple) or immaculate tips; calyx tubes campanulate, 4.4–7.5 mm, lobes erect-ascending.	A. praelongus
103. Corollas white, keel petals rarely with faintly purplish tips; calyx tubes cylindric, 6–8.8 mm, lobes broadly spreading.	A. pattersonii