Astragalus didymocarpus
Bot. Beechey Voy., 334, plate 81. 1838.
Plants (1.5–)3–35(–45) cm, sparsely strigose; taproot slender. Stems erect, ascending, diffuse, or prostrate, sparsely strigose. Leaves (0.8–)1–7.5 cm; stipules (0.5–)1–5 mm, thinly herbaceous becoming papery-membranous; leaflets (7 or)9–17, blades linear-oblanceolate, -elliptic, oblanceolate, oblong-cuneate, or cuneate, 1.5–14 mm, apex deeply retuse, surfaces strigose abaxially, strigose, glabrate, or glabrous adaxially. Peduncles erect or incurved-ascending, (0.5–)1–8 cm. Racemes (5–)7–30-flowered, flowers erect or ascending, straight; axis 0.2–2(–2.2) cm in fruit, not elongating; bracts 0.6–3 mm; bracteoles 0. Pedicels 0.1–0.5(–0.6) mm. Flowers 2.8–10 mm; calyx 2.5–5.7 mm, pilosulous or villosulous, tube 1.5–3.8 mm, lobes subulate to subulate-setaceous, 0.8–2.5 mm; corolla whitish and tinged lavender, or pink-purple with white or pale wing tips; keel 2.4–7.2 mm. Legumes erect or spreading, green or purple-tinged becoming brownish, straight, plumply ovoid or subglobose, somewhat laterally compressed, (2–)2.3–4 × 1.5–3 mm, thinly fleshy becoming stiffly papery, coarsely reticulate or ridged, strigulose, strigulose-hirsutulous, pilosulous, or glabrous; gynophore slender, 0–0.5 mm.
Distribution
sw United States, nw Mexico.
Discussion
Varieties 4 (4 in the flora).
Astragalus didymocarpus has erect flowers and fruits, which contrast with the late anthesis nodding flowers and declined fruits of A. gambelianus.
Selected References
None.
Lower Taxa
Key
| 1 | Keel petals 2.4–4.5 mm. | > 2 |
| 2 | Calyces: hairs mostly black, lobes 0.8–1.4(–2) mm, tubes 1.5–2.8 mm; stems usually erect or ascending, rarely diffuse; Sacramento and San Joaquin valleys s from Contra Costa County and s Coast Ranges, foothills of s California and Channel Islands to Baja California, e Inyo County and adjacent Nevada. | Astragalus didymocarpus var. didymocarpus |
| 2 | Calyces: hairs mostly white, lobes (1.3–)1.6–2.4 mm, tubes 1.7–2.3 mm; stems diffuse, weakly ascending, or prostrate; s Mojave and Colorado deserts, California and Nevada, to c, s Arizona and Mexico. | Astragalus didymocarpus var. dispermus |
| 1 | Keel petals (4.7–)5.3–7.2 mm. | > 3 |
| 3 | Keel petals abruptly incurved, apex broadly rounded; coastal San Luis Obispo and Santa Barbara counties. | Astragalus didymocarpus var. milesianus |
| 3 | Keel petals incurved, apex narrowly triangular, acute or subacute, slightly beaklike; interior s California, Los Angeles County to Baja California. | Astragalus didymocarpus var. obispensis |