Astragalus mollissimus
Ann. Lyceum Nat.Hist. New York 2: 178. 1827.
Plants densely or loosely tuft-forming, acaulescent to subacaulescent or shortly caulescent, (6–)10–30(–45) cm, villous-tomentose. Stems usually few or several, sometimes single, decumbent to ascending, when developed, with several, short internodes, to 2 cm, villous-tomentose. 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. Peduncles ascending, (1.5–)2.5–24 cm. Racemes (5–)7–45-flowered; axis (0.5–)1–18 cm in fruit; bracts 2.5–10(–12) mm; bracteoles 0(–2). Pedicels 0.5–3 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. 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. Seeds 12–38[–41]. 2n = 22.
Distribution
w United States, Mexico.
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).
Selected References
None.
Lower Taxa
Key
| 1 | Legumes glabrous or sparsely pubescent (hispidulous, villous-tomentose, or loosely strigulose). | > 2 |
| 2 | Corollas cream, immaculate; Edwards Plateau, Texas. | Astragalus mollissimus 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. | Astragalus mollissimus var. mollissimus |
| 3 | Calyx tubes 0.8–3(–3.2) mm wide; se New Mexico, trans-Pecos Texas, southward. | Astragalus mollissimus 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). | Astragalus mollissimus 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. | Astragalus mollissimus 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). | Astragalus mollissimus 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. | Astragalus mollissimus 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. | Astragalus mollissimus var. mogollonicus |