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

sentry milkvetch

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 tuft- or cushion-forming, to 2 dm wide, acaulescent or subacaulescent, 0.5–2(–3.2) cm, silvery-strigulose, hairs malpighian; branched caudex with thatch of marcescent stipules and leaf bases.
Stems

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

obscured by stipules and leaf bases.

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.

0.3–2(–3.5) cm;

stipules distinct, 1–3 mm, submembranous becoming papery;

leaflets (3 or)5–9(or 11), blades elliptic, obovate, or suborbiculate, 1.5–5 mm, apex obtuse or subacute, surfaces silvery-strigulose.

Racemes

1–11-flowered, flowers ascending;

axis 0.3–2(–4) cm in fruit;

bracts 2–9 mm;

bracteoles 0.

(1 or)2(or 3)-flowered, flowers ascending;

axis 0.1–0.2 cm;

bracts 0.6–1 mm;

bracteoles 0.

Peduncles

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

axillary, ascending, to 0.5 cm.

Pedicels

1–5 mm.

0.7–1 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.

3.7–8 mm;

calyx campanulate, 2.7–3.6 mm, silky-strigulose, tube 1.7–2.3 mm, lobes subulate, 0.8–1.4 mm;

corolla borne within surface of cushion, pale pink-purple, wing tips whitish, keel maculate;

banner recurved through 45°;

keel 3.7–5.7 mm, apex bluntly deltate, minutely beaklike.

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.

ascending (humistrate), green or purple dotted becoming stramineous, straight, obliquely-ovoid, slightly flattened or basally compressed dorsally, 3–4.5(–4.8) × 2.5 mm, thinly fleshy becoming papery, densely strigulose.

Seeds

14–38(–46).

4–6.

Astragalus purshii

Astragalus cremnophylax

Distribution
from USDA
w North America
[WildflowerSearch map]
[BONAP county map]
from USDA
Arizona
[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.)

Varieties 3 (3 in the flora).

Astragalus cremnophylax, as interpreted here, consists of three (possibly more) obscure and disjunct populations, all within Coconino County. There are few collections of the taxa and measurements presented here are tentative.

(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
1. Leaf rachises lax, soft; plants forming soft cushions; North and South Rim, Grand Canyon, Arizona.
var. cremnophylax
1. Leaf rachises erect or ascending, stiff; plants forming tufts or prickly cushions; Buckskin Mountain, e rim of Marble Canyon, Arizona.
→ 2
2. Banners 7–8 × 5.4–6 mm; keel 5.2–5.7 mm.
var. hevronii
2. Banners 3.7–6.3 × 4–4.6 mm; keel 3.7–4.5 mm.
var. myriorrhaphis
Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Astragalus > sect. Argophylli Fabaceae > subfam. Faboideae > Astragalus > sect. Humillimi
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. 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. 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
A. cremnophylax var. cremnophylax, A. cremnophylax var. hevronii, A. cremnophylax var. myriorrhaphis
Name authority Douglas in W. J. Hooker: Fl. Bor.-Amer. 1: 152. (1831) Barneby: Leafl. W. Bot. 5: 83. (1948)
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