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purple locoweed, woolly locoweed, woolly milkvetch

silver-leaf milkvetch, silveryleaf milkvetch

Habit Plants densely or loosely tuft-forming, acaulescent to subacaulescent or shortly caulescent, (6–)10–30(–45) cm, villous-tomentose. Plants ± mat-forming, acaulescent or subacaulescent, 1.5–12 cm; from superficial caudex, not or seldom with persistent leaf bases, densely pilose or strigulose, hairs usually basifixed (very unequally malpighian in var. alvius).
Stems

usually few or several, sometimes single, decumbent to ascending, when developed, with several, short internodes, to 2 cm, villous-tomentose.

prostrate, 0–10(–15) cm, densely pilose or strigulose.

Leaves

(2–)5–32 cm;

stipules (3–)4–20 mm;

leaflets (9 or)11–35, blades elliptic, suborbiculate, ovate, obovate, rhombic-elliptic, rhombic-obovate, rhombic-ovate, oblong-elliptic, oblanceolate, or oval, (2–)3–30(–45) mm, apex acute, obtuse, retuse, or subacute, surfaces villous-tomentose, sometimes densely so.

1.5–12(–15) cm;

stipules lanceolate, sometimes imbricate, 2–10 mm, submembranous becoming papery;

leaflets 7–21, blades usually elliptic, rhombic-elliptic, rhombic-ovate, obovate-cuneate, elliptic-oblong, elliptic-obovate, oblanceolate, or obovate, rarely elliptic-oblanceolate, 2–15 mm, apex acute, obtuse, or acuminate, surfaces pilose.

Racemes

(5–)7–45-flowered;

axis (0.5–)1–18 cm in fruit;

bracts 2.5–10(–12) mm;

bracteoles 0(–2).

1–6-flowered, flowers ascending;

axis 0.2–2(–2.5) cm in fruit;

bracts 1.8–6.5 mm;

bracteoles 0–2.

Peduncles

ascending, (1.5–)2.5–24 cm.

incurved-ascending, reclined or prostrate in fruit, to 9 cm.

Pedicels

0.5–3 mm.

1.2–3.8 mm.

Flowers

11.8–25 mm;

calyx cylindric to deeply campanulate, 6.8–15.5 mm, villous-tomentose, tube (4.5–)5–13 mm, lobes lanceolate to subulate or subulate-setaceous, 1.6–5.5(–6.8) mm;

corolla pink-purple, pale purple, pinkish, cream, or yellowish suffused with dull lavender, or tipped and suffused or margined with dull purple;

keel 9–20.5 mm.

15–25 mm;

calyx cylindric, 9–16.8 mm, strigulose, hairs white or black, tube 6.8–11.8 mm, lobes linear, 1.6–5(–5.8) mm;

corolla pink-purple or violet to bluish, sometimes fading tan, except keel and wing tips;

banner recurved through 40°;

keel 12–20.3 mm.

Legumes

spreading or ascending, ± straight to incurved through 0.25+ spiral, oblong-ellipsoid, lanceoloid-ellipsoid, ovoid, or ovoid-ellipsoid, sometimes decidedly inflated (not bladdery), terete when narrow, obcompressed when broad, (6–)9–24 × (3–)4–13 mm, fleshy, stiffly papery, leathery, or subligneous, glabrous, puberulent, hispidulous, villosulous, villous-hirsute, villous-tomentulose, or villous-tomentose;

beaks sometimes unilocular.

ascending, brown or stramineous, straight or incurved, ovoid, lanceoloid-ellipsoid, oblong-ellipsoid, or ovoid-acuminate, ± obcompressed, little or no groove ventrally, 15–32(–37) × 5–12(–13) mm, unilocular, fleshy becoming stiffly leathery or woody, strigulose, strigulose-pilosulous, silky-strigose, or villous, hairs appressed or incumbent (sometimes loosely spreading and contorted in var. martini), to 0.4–1(–1.7) mm.

Seeds

12–38[–41].

25–43.

2n

= 22.

Astragalus mollissimus

Astragalus argophyllus

Distribution
from USDA
w United States; Mexico
[WildflowerSearch map]
[BONAP county map]
from USDA
w United States
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 10 (8 in the flora).

The Astragalus mollissimus complex has been variously interpreted as belonging to several species, or has been combined in varietal status under one or more species, or has been split into species each with segregate varieties, and with peripheral taxa still represented at specific rank (D. Isely 1998). Isely (1983) recognized three species within the complex, restricting A. mollissimus to those phases with glabrous or sparsely puberulent fruits, A. bigelovii to the bulk of the remainder with shaggy-hairy fruits, and with A. thompsoniae (whose fruit has a unilocular beak) standing by itself, remote from the remainder of A. bigelovii in the broad sense. Two varieties are exclusive to Mexico: var. irolanus (M. E. Jones) Barneby occurs from Durango and Nuevo León southward to Puebla, and var. nitens Barneby is known from Coahuila. The present treatment follows R. C. Barneby (1964). Some of the varieties, possibly all, are poisonous to domestic livestock, especially to horses (N. Ritter 1917; L. F. James and S. L. Welsh 1992; M. H. Ralphs et al. 2002).

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

Varieties 4 (4 in the flora).

Astragalus argophyllus varies considerably in hair orientation, in flower size and color, and in ecology. Still, it is only with difficulty that material may be sorted into infraspecific taxa, and sometimes plants cannot be satisfactorily identified.

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

Key
1. Legumes glabrous or sparsely pubescent (hispid­ulous, villous-tomentose, or loosely strigulose).
→ 2
2. Corollas cream, immaculate; Edwards Plateau, Texas.
var. coryi
2. Corollas pinkish, pink-purple, pure pale yel­low or yellowish suffused with dull lavender, or tipped and suffused or margined with dull purple; not of Edwards Plateau, Texas.
→ 3
3. Calyx tubes 3.4–4.5 mm wide; plains from Nebraska to New Mexico and w Texas.
var. mollissimus
3. Calyx tubes 0.8–3(–3.2) mm wide; se New Mexico, trans-Pecos Texas, southward.
var. earlei
1. Legumes densely pubescent (villous-tomentose, villous-hirsute, or villous-tomentulose).
→ 4
4. Racemes (5–)7–12-flowered; peduncles (1.5–)2.5–8 cm; legumes broadly ovoid, 7–13 mm wide; e Arizona (Apache County), nw New Mexico (Santa Fe to McKinley County).
var. matthewsii
4. Racemes 7–45-flowered; peduncles 2.5–24 cm; legumes ovoid, lunately ellipsoid, or lanceoloid-ellipsoid, 3–8(–11) mm wide; Arizona, Colorado, Idaho, Nevada, New Mexico, Texas, Utah.
→ 5
5. Legumes ovoid, turgid, 6–11 mm wide, beaks unilocular; Arizona and New Mexico northward to Idaho.
var. thompsoniae
5. Legumes ovoid, lunately ellipsoid or lanceoloid-ellipsoid, usually solid, rarely slightly turgid, 3–8 mm wide, beaks biloc­ular; Arizona, New Mexico, Texas.
→ 6
6. Plants acaulescent; calyces 6.8–9.9 mm; banners 11.8–16.3 mm, keel 10.3–12.5 mm; legumes 6–10 mm; seeds 12–16; trans-Pecos Texas (Presidio and Jeff Davis counties).
var. marcidus
6. Plants acaulescent or shortly caulescent; calyces 10–15.3 mm; banners 16–22.5 mm, keel 12.3–18.6 mm; legumes 9–15 mm; seeds 19–31; Arizona, New Mexico, Texas.
→ 7
7. Plants usually robust, shortly caulescent, stems (0 or)3–17 cm; leaves 9–26 cm, leaflet blades 6–25 mm; keel 13.5–18.5 mm; legume hairs to 1–1.6 mm; se Arizona to extreme w Texas; 1200–1900(–2300) m.
var. bigelovii
7. Plants usually dwarf, acaulescent; stems reduced to thick crowns; leaves (4–)6–16 cm, leaflet blades 3–13 mm; keel 12.5–14.5 mm; legume hairs to 1.6–2.6 mm; plateaus of n Arizona and wc New Mexico, on and near Mogollon Escarpment or north; 1800–2300 m.
var. mogollonicus
1. Banners 18.2–24 mm, keel 15.9–20.3 mm; legumes ovoid to broadly lanceoloid-ellipsoid or oblong-ellipsoid, pubescent but not permanently silky-strigose in age; widespread in w United States.
→ 2
2. Corollas bright purple, banners 22–24 mm; moist meadows, stream banks, or lakeshores in e California, wc to ec and ne Nevada, e Idaho, sw Montana, c, nc, nw Utah.
var. argophyllus
2. Corollas tinged lilac or dull purple, banners 18–21.5(–22.5) mm; dry gravelly hills and mesas, often among sagebrush, of n Arizona, e Nevada, se Idaho, c to ne Utah, sw Wyoming, nw Colorado.
var. martini
1. Banners 15–23.4 mm, keel 12–19.8 mm; legumes lanceoloid-ellipsoid or narrowly and obliquely ovoid-acuminate, silky-strigose even late in season; Arizona, s Utah.
→ 3
3. Banners 15–17.5(–18.4) mm, keel 12–15.2 mm; hairs basifixed.
var. panguicensis
3. Banners 20–23.4 mm, keel 17–19.8 mm; hairs unequally malpighian.
var. alvius
Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Faboideae > Astragalus > sect. Mollissimi Fabaceae > subfam. Faboideae > Astragalus > sect. Argophylli
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. 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
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. 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. mollissimus var. bigelovii, A. mollissimus var. coryi, A. mollissimus var. earlei, A. mollissimus var. marcidus, A. mollissimus var. matthewsii, A. mollissimus var. mogollonicus, A. mollissimus var. mollissimus, A. mollissimus var. thompsoniae
A. argophyllus var. alvius, A. argophyllus var. argophyllus, A. argophyllus var. martini, A. argophyllus var. panguicensis
Name authority Torrey: Ann. Lyceum Nat.Hist. New York 2: 178. (1827) Nuttall in J. Torrey and A. Gray: Fl. N. Amer. 1: 331. (1838)
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