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Pursh's milk-vetch, Pursh's sheeppod, woolly-pod milk-vetch

astragale rustique, cock's-head, field milk-vetch, purple loco, purple loco weed, purple milk vetch

Habit Plants tuft-forming, acaulescent, subacaulescent, or shortly caulescent, 4.5–13 cm, usually villous to villous-tomentose, sometimes appearing white or gray, hairs basifixed; from branched, superficial caudex, branches with thatch. Plants clump-forming, slender, 9–43 cm, strigulose to villous-pilose, sometimes sparsely so; usually from subterranean branched caudex, rarely superficial, branches very long, rhizomatous.
Stems

usually obscured by stipules, or internodes to 2 cm, villous to villous-tomentose.

diffuse or erect to decumbent-clambering, sparsely strigulose-pilosulous.

Leaves

1–12(–15) cm;

stipules (2.5–)3–15 mm, membranous;

leaflets (3 or)5–17(–21), blades obovate, obovate-cuneate, elliptic to oblanceolate, or rhombic-elliptic, 2–14(–20) mm, apex usually acute, subacute, acuminate, or obtuse, rarely truncate-emarginate, surfaces densely villous.

2–10 cm;

stipules (1–)2–11 mm, papery-scarious proximally, submembranous at distal nodes;

leaflets 13–23, blades narrowly elliptic to lanceolate-oblong, 4–18 mm, apex obtuse to retuse or acute, surfaces strigulose.

Racemes

1–11-flowered, flowers ascending;

axis 0.3–2(–4) cm in fruit;

bracts 2–9 mm;

bracteoles 0.

5–15-flowered, flowers ascending-erect;

axis 0.5–2.5 cm in fruit;

bracts 3–7 mm;

bracteoles 0.

Peduncles

ascending or erect, decumbent in fruit, 1.5–10.5 cm.

erect or incurved-ascending, 1.5–15 cm.

Pedicels

1–5 mm.

0.5–1.5 mm.

Flowers

19–25(–27) mm;

calyx cylindric, cylindro-campanulate, or campanulate, (5.5–)6–16(–19) mm, villous-pilose, tube (4–)4.5–12(–13.6) mm, lobes subulate, 1–6(–7) mm;

corolla white, cream, purple, or pink-purple;

banner recurved through 40°;

keel 8–21.2(–22.5) mm.

17–24 mm;

calyx cylindric, 7–12.5 mm, villous, tube 5–7.8 mm, lobes linear, 2.5–5.5 mm;

corolla usually pink-purple, sometimes ochroleucous or nearly white;

keel 11.4–14 mm.

Legumes

initially ascending (humistrate), brownish, not mottled or spotted, incurved, ovoid, ovoid-ellipsoid, or lanceoloid-ellipsoid, dorsiventrally compressed, 7–26(–30) × 3.5–11(–13) mm, unilocular, fleshy becoming leathery, mostly shaggy-villous, sometimes tomentose or villous-hirsute, hairs 1.6–4(–5) mm, often concealing surface;

sessile or subsessile, or gynophore 0.5+ mm.

erect, green becoming dark, ± straight, oblong-ellipsoid, obtusely 3-sided, 7–10 × 2.8–4.5 mm, sulcate abaxially, scarcely swollen, thinly papery, densely silky-villous;

stipe 0.3–1 mm.

Seeds

14–38(–46).

2n

= 16.

Astragalus purshii

Astragalus agrestis

Phenology Flowering May–early Sep.
Habitat Meadows, prairies, hill­sides, stream banks, openings in sagebrush and aspen communities.
Elevation 300–3300 m. (1000–10800 ft.)
Distribution
from USDA
w North America
[WildflowerSearch map]
[BONAP county map]
from FNA
AK; CA; CO; IA; ID; MN; MT; ND; NE; NM; NV; OR; SD; UT; WA; WY; AB; BC; MB; NT; ON; QC; SK; YT; Asia
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 8 (8 in the flora).

The geographic distribution of Astragalus purshii, forming a relatively large triangle in western North America, from southwestern Canada to southern California, northeastward to western North Dakota, makes it the most widely distributed of all astragali with woolly fruits. The case for specific status for such entities as A. inflexus and A. utahensis may be little stronger than that for several of the taxa included within A. purshii (D. Isely 1998). L. Abrams (1944b) often gave an inclusive name of woolly-pod to all of the fuzzy-podded species, sometimes sheep-pod. For consistency they are all called milkvetch here. Isely gave a synopsis that helped to distinguish other woolly fruited species. The treatment of R. C. Barneby (1964) is followed here, and his key to varieties is largely followed.

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

Astragalus agrestis is commonly a sod-forming mesophyte. Since the revision of A. Gray (1864), this species has been associated with A. laxmannii (as the name is applied here), but each belongs to a different phylogenetically natural group, the centers of which are in central Asia and the Near East (R. C. Barneby 1964). The field milkvetch is taxonomically isolated in the American flora but is sufficiently similar to A. danicus Retz from eastern Europe to central Asia (where it overlaps with A. agrestis to some extent) that D. Isely (1998) suggested that A. agrestis is a regional associate of that species. There are indications that the two intergrade in the Altai region of southern Siberia (Barneby).

Astragalus dasyglottis Fischer ex de Candolle is an illegitimate name that applies here.

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

Key
1. Calyces (5.5–)6–10.1 mm; banners 9–16.5 mm; keel 8–13 mm.
→ 2
2. Racemes (3–)5–11-flowered; leaflets (7 or)9–15(or 17); sw Idaho.
var. ophiogenes
2. Racemes 1–5(–7)-flowered; leaflets (3 or)5–9(or 11); California, sw Idaho, nw Nevada, and along foothills and plains adjacent to e slope of Cascades in Oregon.
→ 3
3. Legumes incurved only in beak; seeds 24–32; San Bernardino Mountains and Sierra Nevada, California, w Nevada.
var. lectulus
3. Legumes arched throughout, at least through 0.5–1 spiral; seeds 14–20; plains of ne California to c Oregon, sw Idaho, and nw Nevada.
var. lagopinus
1. Calyces (8–)9–16(–19) mm; banners (14.6–)15.4–25(–26) mm; keel (11.5–)12.4–21.2(–22.5) mm.
→ 4
4. Corollas mostly white or cream (keel tip maculate), rarely banners and wings tipped dull, pale bluish purple; widespread from California and British Columbia eastward to North Dakota and Colorado.
var. purshii
4. Corollas purple or pink-purple throughout; British Columbia to s California (cis- and transmontane), sw Montana, and sc Nevada.
→ 5
5. Banners (14.6–)19–25(–26.5) mm; keel (11.5–)12.4–21(–22.5) mm.
→ 6
6. Plants acaulescent or subacaulescent; leaflets (5 or)7 or 9(or 11), blades obovate, obovate-cuneate, or broadly elliptic, apices obtuse or truncate; ec Idaho, sw Montana.
var. concinnus
6. Plants shortly caulescent or subacau­lescent; leaflets (3 or)5–17(–21), blades obovate-cuneate, oblanceolate, nar­rowly elliptic or elliptic-oblanceolate, apices usually acute, subacute, or short-acuminate, rarely obtuse; British Columbia, California, Idaho, Nevada, Oregon, Utah, Washington.
→ 7
7. Legumes not or very shallowly sulcate ventrally; leaflets (3 or)5–13(–17), blades usually obovate-cuneate or oblanceolate, rarely elliptic-oblanceolate, apices usually acute or subacute, rarely obtuse; racemes 3–11-flowered; banners (14.6–)15.4–25 mm; cis- and trans­montane California, w Nevada, and Oregon.
var. tinctus
7. Legumes strongly depressed-sulcate ventrally in proximal 1/2; leaflets (7 or)9–15(or 17), blades usually narrowly elliptic, rarely elliptic-oblanceolate, apices usually acute or short-acuminate; racemes 2–5(–10)-flowered; banners 19–25(–26.5) mm; Oregon and British Columbia eastward to Utah.
var. glareosus
5. Banners 11.5–18(–25) mm; keel 10.2–15(–20.8) mm.
→ 8
8. Legumes strongly sulcate ventrally in proximal 1/2; c Nevada.
var. pumilio
8. Legumes not or shallowly sulcate ventrally; ne California, sw Idaho, nw Nevada, se Oregon.
→ 9
9. Legumes 13–23(–27) mm; racemes with relatively short (subcapitate) flowering axes; ne California, nw Nevada, e Oregon.
var. tinctus
9. Legumes 8–13 mm; racemes with relatively long flowering axes; along Owyhee, Snake, and lower Bruneau rivers, se Oregon and sw Idaho.
var. ophiogenes
Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Astragalus > sect. Argophylli Fabaceae > subfam. Faboideae > Astragalus > sect. Hypoglottidei
Sibling taxa
A. accidens, A. accumbens, A. ackermanii, A. acutirostris, A. adanus, A. aequalis, A. agnicidus, A. agrestis, A. albens, A. albulus, A. allochrous, A. alpinus, A. altus, A. alvordensis, A. amblytropis, A. americanus, A. amnis-amissi, A. amphioxys, A. ampullarioides, A. ampullarius, A. andersonii, A. anisus, A. anserinus, A. applegatei, A. aquilonius, A. aretioides, A. argophyllus, A. aridus, A. arizonicus, A. arrectus, A. arthurii, A. asclepiadoides, A. asotinensis, A. asymmetricus, A. atratus, A. atropubescens, A. atwoodii, A. austiniae, A. australis, A. barnebyi, A. barrii, A. beathii, A. beatleyae, A. beckwithii, A. bernardinus, A. bibullatus, A. bicristatus, A. bisulcatus, A. bodinii, A. bolanderi, A. bourgovii, A. brandegeei, A. brauntonii, A. brazoensis, A. breweri, A. californicus, A. callithrix, A. calycosus, A. camptopus, A. canadensis, A. caricinus, A. casei, A. castaneiformis, A. castetteri, A. ceramicus, A. cerussatus, A. chamaeleuce, A. chamaemeniscus, A. chinensis, A. chloödes, A. chuskanus, A. cibarius, A. cicer, A. cimae, A. claranus, A. clevelandii, A. cliffordii, A. cobrensis, A. coccineus, A. collinus, A. coltonii, A. columbianus, A. concordius, A. congdonii, A. conjunctus, A. consobrinus, A. contortuplicatus, A. convallarius, A. cottamii, A. crassicarpus, A. cremnophylax, A. cronquistii, A. crotalariae, A. curtipes, A. curvicarpus, A. cusickii, A. cutleri, A. cyaneus, A. cymboides, A. deanei, A. debequaeus, A. desereticus, A. desperatus, A. deterior, A. detritalis, A. diaphanus, A. didymocarpus, A. distortus, A. diversifolius, A. douglasii, A. drabelliformis, A. drummondii, A. duchesnensis, A. eastwoodiae, A. egglestonii, A. emoryanus, A. endopterus, A. ensiformis, A. episcopus, A. equisolensis, A. eremiticus, A. ertterae, A. eucosmus, A. eurekensis, A. eurylobus, A. falcatus, A. feensis, A. filipes, A. flavus, A. flexuosus, A. fucatus, A. funereus, A. gambelianus, A. geyeri, A. gibbsii, A. giganteus, A. gilensis, A. gilmanii, A. gilviflorus, A. glycyphyllos, A. gracilis, A. grayi, A. gypsodes, A. hallii, A. hamiltonii, A. harrisonii, A. heilii, A. henrimontanensis, A. holmgreniorum, A. hoodianus, A. hornii, A. howellii, A. humillimus, A. humistratus, A. hyalinus, A. hypoxylus, A. inflexus, A. insularis, A. inversus, A. inyoensis, A. iodanthus, A. iodopetalus, A. iselyi, A. jaegerianus, A. jejunus, A. johannis-howellii, A. kelseyae, A. kentrophyta, A. kerrii, A. knightii, A. laccoliticus, A. lancearius, A. laxmannii, A. layneae, A. leibergii, A. lemmonii, A. lentiformis, A. lentiginosus, A. leptaleus, A. leptocarpus, A. leucolobus, A. limnocharis, A. lindheimeri, A. linifolius, A. loanus, A. lonchocarpus, A. lotiflorus, A. lutosus, A. lyallii, A. macrodon, A. magdalenae, A. malacoides, A. malacus, A. megacarpus, A. michauxii, A. microcymbus, A. microcystis, A. microlobium, A. micromerius, A. miguelensis, A. minthorniae, A. misellus, A. miser, A. missouriensis, A. moencoppensis, A. mohavensis, A. mollissimus, A. molybdenus, A. monoensis, A. montii, A. monumentalis, A. mulfordiae, A. multiflorus, A. musiniensis, A. naturitensis, A. neglectus, A. nelsonianus, A. neomexicanus, A. nevinii, A. newberryi, A. nidularius, A. nothoxys, A. nudisiliquus, A. nutans, A. nutriosensis, A. nuttallianus, A. nuttallii, A. nutzotinensis, A. nyensis, A. obcordatus, A. obscurus, A. oniciformis, A. oocalycis, A. oocarpus, A. oophorus, A. oreganus, A. osterhoutii, A. oxyphysus, A. pachypus, A. palmeri, A. panamintensis, A. pardalinus, A. parryi, A. pattersonii, A. pauperculus, A. paysonii, A. peckii, A. pectinatus, A. perianus, A. phoenix, A. pictiformis, A. pinonis, A. piscator, A. piutensis, A. plattensis, A. platytropis, A. polaris, A. pomonensis, A. porrectus, A. praelongus, A. preussii, A. proimanthus, A. proximus, A. pseudiodanthus, A. pterocarpus, A. pubentissimus, A. pulsiferae, A. puniceus, A. pycnostachyus, A. racemosus, A. rafaelensis, A. rattanii, A. ravenii, A. recurvus, A. reflexus, A. remotus, A. reventiformis, A. reventus, A. riparius, A. ripleyi, A. robbinsii, A. rusbyi, A. sabulonum, A. sabulosus, A. salmonis, A. saurinus, A. scaphoides, A. schmolliae, A. sclerocarpus, A. scopulorum, A. sepultipes, A. serenoi, A. sericoleucus, A. serpens, A. sesquiflorus, A. sheldonii, A. shevockii, A. shortianus, A. siliceus, A. simplicifolius, A. sinuatus, A. solitarius, A. sophoroides, A. soxmaniorum, A. spaldingii, A. sparsiflorus, A. spatulatus, A. speirocarpus, A. straturensis, A. striatiflorus, A. subcinereus, A. subvestitus, A. succumbens, A. tegetarioides, A. tener, A. tennesseensis, A. tephrodes, A. terminalis, A. tetrapterus, A. thurberi, A. tibetanus, A. tidestromii, A. tiehmii, A. titanophilus, A. toanus, A. toquimanus, A. tortipes, A. traskiae, A. tricarinatus, A. trichopodus, A. tridactylicus, A. troglodytus, A. tweedyi, A. tyghensis, A. umbellatus, A. umbraticus, A. uncialis, A. utahensis, A. vaccarum, A. vallaris, A. vexilliflexus, A. villosus, A. wardii, A. waterfallii, A. webberi, A. welshii, A. wetherillii, A. whitneyi, A. williamsii, A. wingatanus, A. wittmannii, A. woodruffii, A. wootonii, A. wrightii, A. xiphoides, A. yoderwilliamsii, A. zionis
A. accidens, A. accumbens, A. ackermanii, A. acutirostris, A. adanus, A. aequalis, A. agnicidus, A. albens, A. albulus, A. allochrous, A. alpinus, A. altus, A. alvordensis, A. amblytropis, A. americanus, A. amnis-amissi, A. amphioxys, A. ampullarioides, A. ampullarius, A. andersonii, A. anisus, A. anserinus, A. applegatei, A. aquilonius, A. aretioides, A. argophyllus, A. aridus, A. arizonicus, A. arrectus, A. arthurii, A. asclepiadoides, A. asotinensis, A. asymmetricus, A. atratus, A. atropubescens, A. atwoodii, A. austiniae, A. australis, A. barnebyi, A. barrii, A. beathii, A. beatleyae, A. beckwithii, A. bernardinus, A. bibullatus, A. bicristatus, A. bisulcatus, A. bodinii, A. bolanderi, A. bourgovii, A. brandegeei, A. brauntonii, A. brazoensis, A. breweri, A. californicus, A. callithrix, A. calycosus, A. camptopus, A. canadensis, A. caricinus, A. casei, A. castaneiformis, A. castetteri, A. ceramicus, A. cerussatus, A. chamaeleuce, A. chamaemeniscus, A. chinensis, A. chloödes, A. chuskanus, A. cibarius, A. cicer, A. cimae, A. claranus, A. clevelandii, A. cliffordii, A. cobrensis, A. coccineus, A. collinus, A. coltonii, A. columbianus, A. concordius, A. congdonii, A. conjunctus, A. consobrinus, A. contortuplicatus, A. convallarius, A. cottamii, A. crassicarpus, A. cremnophylax, A. cronquistii, A. crotalariae, A. curtipes, A. curvicarpus, A. cusickii, A. cutleri, A. cyaneus, A. cymboides, A. deanei, A. debequaeus, A. desereticus, A. desperatus, A. deterior, A. detritalis, A. diaphanus, A. didymocarpus, A. distortus, A. diversifolius, A. douglasii, A. drabelliformis, A. drummondii, A. duchesnensis, A. eastwoodiae, A. egglestonii, A. emoryanus, A. endopterus, A. ensiformis, A. episcopus, A. equisolensis, A. eremiticus, A. ertterae, A. eucosmus, A. eurekensis, A. eurylobus, A. falcatus, A. feensis, A. filipes, A. flavus, A. flexuosus, A. fucatus, A. funereus, A. gambelianus, A. geyeri, A. gibbsii, A. giganteus, A. gilensis, A. gilmanii, A. gilviflorus, A. glycyphyllos, A. gracilis, A. grayi, A. gypsodes, A. hallii, A. hamiltonii, A. harrisonii, A. heilii, A. henrimontanensis, A. holmgreniorum, A. hoodianus, A. hornii, A. howellii, A. humillimus, A. humistratus, A. hyalinus, A. hypoxylus, A. inflexus, A. insularis, A. inversus, A. inyoensis, A. iodanthus, A. iodopetalus, A. iselyi, A. jaegerianus, A. jejunus, A. johannis-howellii, A. kelseyae, A. kentrophyta, A. kerrii, A. knightii, A. laccoliticus, A. lancearius, A. laxmannii, A. layneae, A. leibergii, A. lemmonii, A. lentiformis, A. lentiginosus, A. leptaleus, A. leptocarpus, A. leucolobus, A. limnocharis, A. lindheimeri, A. linifolius, A. loanus, A. lonchocarpus, A. lotiflorus, A. lutosus, A. lyallii, A. macrodon, A. magdalenae, A. malacoides, A. malacus, A. megacarpus, A. michauxii, A. microcymbus, A. microcystis, A. microlobium, A. micromerius, A. miguelensis, A. minthorniae, A. misellus, A. miser, A. missouriensis, A. moencoppensis, A. mohavensis, A. mollissimus, A. molybdenus, A. monoensis, A. montii, A. monumentalis, A. mulfordiae, A. multiflorus, A. musiniensis, A. naturitensis, A. neglectus, A. nelsonianus, A. neomexicanus, A. nevinii, A. newberryi, A. nidularius, A. nothoxys, A. nudisiliquus, A. nutans, A. nutriosensis, A. nuttallianus, A. nuttallii, A. nutzotinensis, A. nyensis, A. obcordatus, A. obscurus, A. oniciformis, A. oocalycis, A. oocarpus, A. oophorus, A. oreganus, A. osterhoutii, A. oxyphysus, A. pachypus, A. palmeri, A. panamintensis, A. pardalinus, A. parryi, A. pattersonii, A. pauperculus, A. paysonii, A. peckii, A. pectinatus, A. perianus, A. phoenix, A. pictiformis, A. pinonis, A. piscator, A. piutensis, A. plattensis, A. platytropis, A. polaris, A. pomonensis, A. porrectus, A. praelongus, A. preussii, A. proimanthus, A. proximus, A. pseudiodanthus, A. pterocarpus, A. pubentissimus, A. pulsiferae, A. puniceus, A. purshii, A. pycnostachyus, A. racemosus, A. rafaelensis, A. rattanii, A. ravenii, A. recurvus, A. reflexus, A. remotus, A. reventiformis, A. reventus, A. riparius, A. ripleyi, A. robbinsii, A. rusbyi, A. sabulonum, A. sabulosus, A. salmonis, A. saurinus, A. scaphoides, A. schmolliae, A. sclerocarpus, A. scopulorum, A. sepultipes, A. serenoi, A. sericoleucus, A. serpens, A. sesquiflorus, A. sheldonii, A. shevockii, A. shortianus, A. siliceus, A. simplicifolius, A. sinuatus, A. solitarius, A. sophoroides, A. soxmaniorum, A. spaldingii, A. sparsiflorus, A. spatulatus, A. speirocarpus, A. straturensis, A. striatiflorus, A. subcinereus, A. subvestitus, A. succumbens, A. tegetarioides, A. tener, A. tennesseensis, A. tephrodes, A. terminalis, A. tetrapterus, A. thurberi, A. tibetanus, A. tidestromii, A. tiehmii, A. titanophilus, A. toanus, A. toquimanus, A. tortipes, A. traskiae, A. tricarinatus, A. trichopodus, A. tridactylicus, A. troglodytus, A. tweedyi, A. tyghensis, A. umbellatus, A. umbraticus, A. uncialis, A. utahensis, A. vaccarum, A. vallaris, A. vexilliflexus, A. villosus, A. wardii, A. waterfallii, A. webberi, A. welshii, A. wetherillii, A. whitneyi, A. williamsii, A. wingatanus, A. wittmannii, A. woodruffii, A. wootonii, A. wrightii, A. xiphoides, A. yoderwilliamsii, A. zionis
Subordinate taxa
A. purshii var. concinnus, A. purshii var. glareosus, A. purshii var. lagopinus, A. purshii var. lectulus, A. purshii var. ophiogenes, A. purshii var. pumilio, A. purshii var. purshii, A. purshii var. tinctus
Synonyms A. goniatus
Name authority Douglas in W. J. Hooker: Fl. Bor.-Amer. 1: 152. (1831) Douglas ex G. Don: Gen. Hist. 2: 258. (1832)
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