Astragalus purshii |
Astragalus howellii |
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Pursh's milkvetch, woollypod milkvetch |
Howell's milkvetch |
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Habit | Plants perennial, acaulescent to shortly caulescent, densely villous to villous-tomentose, hairs basifixed. | Plants perennial, caulescent, villosulous, hairs basifixed. |
Stems | prostrate, loosely to densely tufted, 0–20 cm. |
several, ascending to erect, forming bushy clumps, 5–40 cm. |
Leaves | 1–12(17) cm; leaflets (3)5–17(21), elliptic to oblanceolate, 2–14(20) × 1–7 mm; tips obtuse to acute; surfaces densely villous; stipules 2.5–15 mm; free. |
(4)5–14 cm; leaflets (17)21–27(33), oblong, obovate-cuneate or oblanceolate, 4–14 × 1–4 mm; tips obtuse to truncate-retuse; surfaces pubescent, adaxially sometimes glabrate to glabrous; stipules 3–5 mm; free. |
Inflorescences | racemes or subumbels, 1–12-flowered; peduncles 1–14 cm; bracts 4–9 mm; pedicels 2–4.3 mm; bracteoles 0–2. |
racemes loosely 10–25-flowered; peduncles 5.5–18 cm; bracts 1–2.5 mm; pedicels 1–4.5 mm; bracteoles 0. |
Flowers | ascending at anthesis; calyces 5.5–16(19) mm, often purple, villous-pilose with white or mixed white and black hairs; tubes 8.5–12.5 mm; teeth subulate, 2.2–6 mm; corollas 19–27 mm; whitish to ochroleucous or pink-purple; ovules 14–40(46). |
spreading or declined at anthesis; calyces 5–8 mm, strigose or villosulous with white or sometimes black hairs; tubes 4–5 mm; teeth subulatetriangular, 1–3 mm; corollas 6.5–8.5 mm, ochroleucous, unspotted; ovules 11–21. |
Fruits | unilocular, ascending, obliquely ovoid, usually curved, obcompressed, scarcely to deeply sulcate; (7)13–27(30) × 3.5–11 mm, densely white to tawny tomentose or densely villous; hairs nearly always concealing valve surfaces; valves coriaceous, sessile or on gynophores 0–1.6 mm. |
bilocular, pendulous, lunately lanceolate or linear-lanceolate, trigonously compressed; (16)20–30 × 3–5 mm, densely villosulous; valves stiffly papery; stipes (4)7–12(14) mm. |
Astragalus purshii |
Astragalus howellii |
|
Distribution | ||
Discussion | Western North America. ~8 varieties; 4 varieties treated in Flora. Throughout western North America, particularly in the Intermountain Region, this is a low, tufted milkvetch with white or gray villous hairs and pods resembling balls of cotton. Barneby (1964) stated, “Attempts to devise a practical key to the varieties of A. purshii are never wholly successful.” Variety ophiogenes, the Snake River milkvetch, a native of Idaho, has been reported from Malheur County, but this is apparently based on misidentifications of A. purshii var. lagopinus. Variety ophiogenes has 3–11-flowered racemes and 9–17 leaflets. |
Scabland, dry rocky slopes and ridges, grassy hills. Flowering Apr–Jun. 50–1600 m. BW, Col. WA. Native. |
Source | Flora of Oregon, volume 2, page 671 Richard Halse |
Flora of Oregon, volume 2, page 665 Richard Halse |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Astragalus purshii var. ophiogenes | Astragalus howellii var. howellii |
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