Flora of North America species comparison

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Acmispon denticulatus

Acmispon

meadow birds-foot trefoil, meadow lotus, Mohave trefoil, riverbar bird's-foot-trefoil, riverbar lotus, riverbar trefoil, tooth lotus

deervetch, deerweed, lotus
Habit Herbs, annual, cespitose, often glaucous, 0.3–4 dm, not fleshy, glabrous or hirsute; taprooted. Herbs, annual or perennial, shrubs or subshrubs, unarmed.
Stems

1(–5), decumbent to erect, apically or basally coarse-branched, herbaceous, leafy.

procumbent or decumbent to ascending or erect, glabrous or pubescent.
Leaves

subpinnate, pinnate, or palmate;

stipules glandlike or absent; petiolate;

rachis 5–12 mm, flattened;

leaflets 2–4, often 1 or 2 on one side and 2 terminal, blades elliptic to obovate (lateral sometimes asymmetric), margins denticulate or entire, apex acute to obtuse, surfaces hirsute.

alternate, odd- or even-pinnate, palmate, or subpalmate;

stipules usually present, glandlike, ovate, or conic, sometimes absent;

sessile, subsessile, or petiolate;

leaflets (2 or)3–10(–12), blade margins usually entire (sometimes denticulate in A. americanus, A. denticulatus), surfaces usually pubescent, rarely glabrous.
Inflorescences

1 or 2-flowered.

solitary flowers or 2–12(–20)-flowered umbels, axillary;

bracts present, usually subtending umbel or distal on pedicel, or absent.
Peduncles

± sessile;

bract absent.

Flowers

5–8 mm;

calyx 3–5 mm, tube hirsute or glabrous, lobes subulate, ± denticulate;

corolla cream-white to pale yellow, banner purple-tinged, keel tip yellowish, claws shorter to slightly longer than calyx tube, banner ascending, wings ± equaling keel, with deep, triangular auricle;

style curved, glabrous.

papilionaceous;

calyx symmetric, bell-shaped or short-cylindric, lobes 5;

corolla yellow to orange-yellow, cream, greenish white, white, pink, salmon, or pinkish red, sometimes marked with red, turning pink, orange, red, or brown, banner equaling or shorter than wings, wings symmetric or asymmetric, one wing ± above and one under keel;

stamens 10, diadelphous;

anthers basifixed, longitudinal;

style with or without collar;

stigma terminal.
Fruits

legumes, persistent or deciduous at base of pedicel with persistent calyx, included to ± strongly exserted from calyx, sessile, straight or ± curved to arched at apex, deflexed or not, usually linear to oblong or ovoid, rarely lanceoloid, abruptly short-beaked or tapered into an incurved beak exserted from calyx and appearing hooked, dehiscent or indehiscent, glabrous, glabrate, or ± strigillose to villous or silky.
Legumes

persistent, solitary or paired, exserted, erect or spreading, tawny, straight, compressed, slightly constricted, not septate, widely oblong, 8–20 × 3 mm, leathery, apex abruptly downward angled and curved, dehiscent, smooth, margins often undulate-verrucose, strigose or glabrous.

Seeds

(2 or)3(or 4), gray, faintly mottled, asymmetrically ± angular-obovoid, flattened, smooth.

1–10(–30), mottled or not, oblong, obovoid, ovoid, elliptic, lenticular, globose, subglobose, reniform, or cylindric.
x

= 6, 7.
2n

= 12.

Acmispon denticulatus

Acmispon
Phenology Flowering spring–summer.
Habitat Grassy slopes, meadows, prairies, clearings, gravel bars, stream banks, vernal pools, pastures, grainfields, usually sandy soils, sometimes alkali, clay, or serpentine soils, roadsides.
Elevation 0–1900 m. (0–6200 ft.)
Distribution
from FNA
CA; ID; OR; UT; WA; BC
[WildflowerSearch map]
[BONAP county map]
North America; nw Mexico; South America (Chile)
[BONAP county map]
Discussion

Acmispon denticulatus occurs in California from the San Francisco Bay area, Sacramento Valley, and northern Sierra Nevada Foothills to the northwest, Cascade Range and Modoc Plateau, into adjacent southern Oregon (Siskiyou and Klamath regions), northward on both sides of the Cascade Range into southern British Columbia, with eastern outliers in southwestern Utah (Washington County), and in south-central Idaho (Lincoln County).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Species 34 (28 in the flora).

Six species of Acmispon are found only in Mexico [A. flexuosus (Greene) Brouillet, A. niveus (S. Watson) Brouillet, A. nudatus (Greene) Brouillet, A. oroboides (Kunth) Brouillet, A. watsonii (Vasey & Rose) Brouillet] or in Chile [A. subpinnatus (Lagasca) D. D. Sokoloff].

Throughout the twentieth century, Acmispon was usually included within Lotus (D. Isely 1981, 1993). Recent phylogenetic work, both morphologic (A. M. Arambarri 2000) and molecular (G. J. Allan and J. M. Porter 2000; Allan et al. 2003; D. D. Sokoloff et al. 2007), has shown that Acmispon is distinct from the Eurasian Lotus and the North American Hosackia. Notable differences among the three genera include the leafy or scarious, caducous stipules in Hosackia (where leaves are odd-pinnate) versus glandlike in Lotus (leaves with a pair of basal leaflets in stipular position with three palmate terminal leaflets) and Acmispon (leaves odd- or even-pinnate, palmate, or subpalmate).

In Acmispon and Hosackia, the banner sometimes is implicate, remaining folded longitudinally and enclosing the rest of the petals; if the banner is implicate-ascending, it remains folded but is partially raised above the other petals.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Key
1. Shrubs or subshrubs (sometimes perennial herbs in A. procumbens), usually bushy or erect to procumbent, rarely mat-forming, prostrate, or cespitose.
→ 2
2. Leaves usually subpalmate (sometimes only distally), sometimes pinnate, leaflets 3 (except A. glaber sometimes to 7); inflorescences 1–3(–7)-flowered.
→ 3
3. Herbs perennial, sometimes subshrubs, gray-canescent or strigose; stems leafy; wings longer than keel; seeds 2 or 3+.
A. procumbens
3. Subshrubs, green, strigose, strigillose, or glabrous; stems remotely leafy; wings shorter than or equaling keel; seeds 1 or 2.
→ 4
4. Leaf rachises 2–8(–10) mm; leaflet blades elliptic to lanceolate, apex acute; inflorescences (1 or)2–7-flowered; flowers 7–12 mm; petal claws slightly longer than calyx tube; legumes greenish to reddish brown, linear-oblong, curved to ± straight, 10–15 mm, smooth.
A. glaber
4. Leaf rachises absent; leaflet blades elliptic, apex obtuse; inflorescences 1(or 2)-flowered; flowers 4–5 mm; petal claws shorter than calyx tube; legumes tawny, oblong, curved, (5–)6–9 mm, finely veined.
A. haydonii
2. Leaves pinnate (usually irregularly) or subpalmate, leaflets 3–6; inflorescences (1 or)2–12-flowered.
→ 5
5. Plants green or gray; stems erect or decumbent, woody; leaflet blades sparsely to densely strigose (and wings ± equaling keel); California Channel Islands.
A. dendroideus
5. Plants green, greenish, or brownish; stems usually procumbent to ± ascending, sometimes erect to spreading (wiry or stout), herbaceous, sometimes ± woody; leaflet blades strigillose or strigose (and wings longer than keel in A. rigidus), to glabrate or glabrous; mainland w United States, nw Mexico.
→ 6
6. Leaflet blades strigose; peduncles much longer than leaves, 20–60(–130) mm; legumes dehiscent, straight, short-beaked; seeds 18–30.
A. rigidus
6. Leaflet blades strigillose to glabrate or glabrous; peduncles shorter than leaves, 0–10 mm, or if longer, to 25 mm; legumes indehiscent, usually curved, sometimes straight, beaked to long-beaked; seeds 1 or 2.
→ 7
7. Plants often bushy, sometimes mat-forming, robust, 5–20 dm; stems usually erect to spreading, sometimes procumbent, herbaceous, slender, remotely leafy; inflorescences in axil of distal leaves, spaced or congested, peduncles 0–2 mm; legumes curved to ± straight.
A. glaber
7. Plants usually mat-forming, cespitose, or prostrate, sometimes bushy or wiry, 0.8–8 dm; stems procumbent to ascending, wiry, thick or stout, leafy; inflorescence peduncles 1–25 mm; legumes arched.
→ 8
8. Stems greenish; flowers 8–10 mm; petal claws shorter than calyx tube, wings slightly longer than keel; legumes mostly included.
A. cytisoides
8. Stems brownish; flowers 6–8 mm; petal claws longer than calyx tube, wings shorter than keel (and other petals); legumes ± exserted.
A. junceus
1. Herbs annual or perennial (rarely subshrubs), mat-forming, cespitose, or prostrate.
→ 9
9. Herbs annual, cespitose, sometimes mat-forming or solitary; taprooted.
→ 10
10. Inflorescences 2–8-flowered; legumes indehiscent, strongly exserted from calyx, arched, turgid, constricted between seeds; seeds 2, mottled.
→ 11
11. Stems remotely leafy; inflorescences 3–8-flowered, peduncles 8–30 mm; flowers 5–7 mm, claws longer than calyx tube, wings equaling or longer than keel; legumes glabrous.
A. prostratus
11. Stems leafy; inflorescences 2–5-flowered, peduncles 1–2(–5) mm; flowers 3–4(–5) mm, claws shorter than calyx tube, wings shorter than keel; legumes strigillose.
A. micranthus
10. Inflorescences 1 or 2(–5)-flowered; legumes dehiscent, exserted from calyx (except mostly included in A. rubriflorus), usually straight or ± curved, compressed, not or slightly constricted between seeds; seeds 2–10, not or faintly or ± mottled (often black-mottled in A. americanus).
→ 12
12. Leaves tomentose or tomentulose to glabrate; wings equaling or longer than keel, styles puberulent or glabrous.
→ 13
13. Herbs usually mat-forming, sometimes cespitose, strigillose, hirsute, canescent-tomentose, or scantily pubescent; wings longer than keel.
A. strigosus
13. Herbs not mat-forming (rounded, straggly), glabrate; wings equaling keel.
A. intricatus
12. Leaves glabrous, sparsely appressed-hairy, hirsute, or villous to pubescent, strigillose, or strigose; wings ± equaling or shorter than keel; styles glabrous.
→ 14
14. Plants usually glabrous or strigillose, sometimes glabrate to ± pilose; inflorescences 1–5-flowered; peduncles (0–)3–25 mm, bracts usually 1–3-foliolate, rarely absent; legumes straight or ± curved; seeds 3–9.
→ 15
15. Plants ± fleshy; stems procumbent to ascending; leaves pinnate, leaflets (3–)5–7; inflorescences 1–5-flowered, pedunculate; corollas bright yellow or orange-yellow; legumes leathery.
A. maritimus
15. Plants not fleshy; stems erect to procumbent; leaves pinnate or palmate, leaflets (1–)3–5; inflorescences 1 or 2-flowered, subsessile or pedunculate; corollas pink or salmon, or whitish or cream; legumes thinly leathery.
→ 16
16. Leaflet blades obovate to oblong or elliptic, apex obtuse, surfaces strigose; flowers (2.5–)4–6 mm, calyx tube sparsely strigillose, corollas pink or salmon, claws longer than calyx tube; legumes hook-beaked; seeds not mottled.
A. parviflorus
16. Leaflet blades obovate, ovate, or elliptic to lanceolate, apex acute, surfaces sparsely appressed-hairy; flowers (4–)5–9 mm, calyx tube pilose, corollas whitish or cream, claws shorter than calyx tube; legume apex abruptly downward angled and curved; seeds often black-mottled.
A. americanus
14. Plants usually hirsute, villous, or pubescent, sometimes glabrate or glabrous; inflorescences 1 or 2-flowered; peduncles 0–2 mm, bracts absent; legumes straight; seeds 2–4(–7).
→ 17
17. Stems decumbent to ascending or erect; leaflet blades hirsute or villous; calyx lobes subulate; corollas cream-white to pale yellow and banner purple-tinged, or bright pinkish red.
→ 18
18. Leaves petiolate, rachises 5–12 mm, leaflet blades elliptic to obo­vate; legumes exserted, 8–20 mm, leathery, strigose or glabrous.
A. denticulatus
18. Leaves subsessile, rachises 4–6 mm, leaflet blades lanceolate; legumes mostly included, 8–9 mm, papery, villous.
A. rubriflorus
17. Stems procumbent to low-ascending; leaflet blades villous or pubescent; calyx lobes lanceolate; corollas yellow, or pale yellow and reddish-tipped.
→ 19
19. Plants not fleshy; leaves petiolate; wings shorter than keel; legumes thinly leathery, pubescent (to glabrate), ± septate.
A. wrangelianus
19. Plants ± fleshy; leaves subsessile or sessile; wings ± equaling keel; legumes stiffly papery, villous, not septate.
A. brachycarpus
9. Herbs perennial (rarely subshrubs), usually mat-forming, sometimes bushy, from woody caudices, rhizomatous caudices, or woody-taprooted.
→ 20
20. Flowers 4–12 mm; styles curved, geniculate 90°, or incurved; legumes indehiscent, strongly arched or curved, sometimes ± straight, apex tapering, short- or long-beaked, beak sometimes curved; leaves subpalmate, sometimes irregularly pinnate.
→ 21
21. Leaves subpalmate, leaflets usually 3, blades canescent to strigose; stems gray-canescent or strigose; calyx tube ± densely strigose; petal claws longer than calyx tube, wings longer than keel; seeds 2 or 3+.
A. procumbens
21. Leaves irregularly pinnate or subpalmate, leaflets 3–6(or 7), blades pilose, villous, or densely sericeous; stems tomentose to canescent, strigose, or ± villous (young) to glabrate (mature); calyx tube villous or sparsely or densely villosulous; petal claws shorter than or equaling calyx tube; seeds 1 or 2(or 3).
→ 22
22. Leaflet blades sparsely to densely pilose; flowers 4–6(–7) mm, calyx lobes setaceous; legumes 3–5 mm, villous.
A. tomentosus
22. Leaflet blades villous or densely sericeous; flowers 4.5–12 mm, calyx lobes subulate; legumes 6–10 mm, strigillose or glabrate to silky.
→ 23
23. Stems ± villous to glabrate; leaflet blades villous; calyx tube sparsely villosulous; corollas: wings longer than keel; legumes exserted, ovoid- ellipsoid, strigillose.
A. decumbens
23. Stems tomentose to canescent or strigose; leaflet blades densely sericeous; calyx tube densely villous; corollas: wings ± equaling keel; legumes included to moderately(–strongly) exserted, lanceoloid, glabrate to silky.
A. argophyllus
20. Flowers 5–25 mm; styles straight or slightly curved, sometimes basally curved; legumes dehiscent, usually straight, ± curved, or curved distally, apex short-beaked; leaves palmate or pinnate, or subpalmate to irregularly pinnate.
→ 24
24. Stems stiff; leaves palmate and leaflets villous to strigose.
→ 25
25. Leaves sessile; inflorescences (1 or)2–5(or 6)-flowered, peduncles longer than leaves, (10–)20–50(–80) mm, bracts 1–3-foliolate; banners recurved ca. 45°.
A. utahensis
25. Leaves short-petiolate proximally, subsessile or sessile distally; inflorescences 1 or 2-flowered, peduncles usually longer, sometimes shorter, than leaves, 0–30 mm, bracts absent or (when pedunculate) unifoliolate; banners implicate-ascending.
A. wrightii
24. Stems herbaceous; leaves pinnate to subpalmate (distal) and leaflets gray-puberulent, villous, tomentose, strigose, strigillose, or puberulent, or if palmate, then leaflets seri­ceous to canescent.
→ 26
26. Leaves pinnate, leaflets 7–9(–12); corollas greenish white, white, or yellow, fading rose or reddish.
A. grandiflorus
26. Leaves pinnate or subpalmate, leaflets 3–5(–7)[–13]; corollas usually yellow or cream to orange-yellow.
→ 27
27. Petal claws ± equaling calyx tube; flowers 5–16(–20) mm; legumes straight or ± curved, slightly constricted between seeds.
→ 28
28. Plants silvery or gray, sericeous to canescent; rachises 1–4 mm; legumes turgid.
A. argyraeus
28. Plants green, ± strigose to puberulent; rachises (1.5–)5–10 mm; legumes compressed.
A. plebeius
27. Petal claws shorter than calyx tube; flowers (10–)12–22 mm; legumes straight, not constricted between seeds.
→ 29
29. Plants greenish, densely hirsute; leaf blades villous to tomentose; inflo­rescences 1–3(–5)-flowered; calyx tubes densely villous; banners obliquely ascending.
A. neomexicanus
29. Plants silvery, tomentose; leaf blades gray-puberulent; inflorescences (1 or)2–7-flowered; calyx tubes puberulent; banners ascending 45–90°.
A. mearnsii
Source FNA vol. 11. FNA vol. 11. Author: Luc Brouillet.
Parent taxa Fabaceae > subfam. Faboideae > Acmispon Fabaceae > subfam. Faboideae
Sibling taxa
A. americanus, A. argophyllus, A. argyraeus, A. brachycarpus, A. cytisoides, A. decumbens, A. dendroideus, A. glaber, A. grandiflorus, A. haydonii, A. intricatus, A. junceus, A. maritimus, A. mearnsii, A. micranthus, A. neomexicanus, A. parviflorus, A. plebeius, A. procumbens, A. prostratus, A. rigidus, A. rubriflorus, A. strigosus, A. tomentosus, A. utahensis, A. wrangelianus, A. wrightii
Subordinate taxa
A. americanus, A. argophyllus, A. argyraeus, A. brachycarpus, A. cytisoides, A. decumbens, A. dendroideus, A. denticulatus, A. glaber, A. grandiflorus, A. haydonii, A. intricatus, A. junceus, A. maritimus, A. mearnsii, A. micranthus, A. neomexicanus, A. parviflorus, A. plebeius, A. procumbens, A. prostratus, A. rigidus, A. rubriflorus, A. strigosus, A. tomentosus, A. utahensis, A. wrangelianus, A. wrightii
Synonyms Hosackia denticulata, Anisolotus denticulatus, Lotus denticulatus A. section anisolotus, A. section simpeteria, Anisolotus, Lotus section simpeteria, Ottleya, Syrmatium
Name authority (Drew) D. D. Sokoloff: Ann. Bot. Fenn. 37: 130. (2000) Rafinesque: Atlantic J. 1: 144. (1832)
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Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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