Astragalus coltonii
Plants clump-forming, 10–75 cm, strigulose, canescent, cinereous, or greenish cinereous; from subterranean or branched, superficial caudex. Stems erect or ascending, strigulose, canescent, cinereous, or greenish cinereous. Leaves dimorphic, some unifoliolate distally and reduced to phyllodia, continuous with rachis, 2–10 cm; stipules distinct throughout, 1–7 mm, papery at proximal nodes, herbaceous at distal nodes; leaflets (1 or)3–19, blades linear, oblong, cuneate-oblong, or ovate, (3–)4–20 mm, apex acute, obtuse, truncate or retuse, surfaces strigose; terminal leaflet decurrent distally, not jointed to rachis. Peduncles erect or incurved-ascending, (4–)6.5–30 cm. Racemes (2–)5–30-flowered, flowers spreading-declined; axis 3–20 cm in fruit; bracts 0.5–3.2 mm; bracteoles 0. Pedicels 0.8–2.5 mm. Flowers 12–19 mm; calyx purplish, cylindric, 4.5–8 mm, strigose, tube 4–6.7 mm, lobes broadly subulate, 0.6–2.3 mm; corolla pink-purple; banner recurved through 35–50°; keel 9–13 mm, apex bluntly or sharply deltate. Legumes pendulous, green or reddish becoming stramineous, straight or gently decurved, oblong to oblanceoloid, strongly compressed, flattened laterally, 19–35 × (3–)3.5–6 mm, stiffly papery, glabrous; stipe 4–11 mm. Seeds 14–20.
Distribution
w United States.
Discussion
Varieties 2 (2 in the flora).
R. C. Barneby (1964) aligned Astragalus coltonii with A. filipes in Homalobus or the equivalent sect. Homalobi. Although A. filipes is similar with its compressed and stipitate fruit, the stipules are fundamentally different. P. A. Rydberg (1929) and M. E. Jones (1923) described the stipules of A. coltonii as connate; proximal stipules do form a bidentate, more or less amplexicaul sheath, but the interpretation is not strictly correct. The stipules are united by adherence to a vestigial petiole and are consistent with all genuine sect. Lonchocarpi and not like those in A. filipes, which are united by their contrapetiolar margins.
Selected References
None.
Key
| 1 | Leaves odd-pinnate or distalmost unifoliolate; leaflets (1 or)3–11, terminal leaflet each confluent with rachis. | Astragalus coltonii var. coltonii |
| 1 | Leaves odd-pinnate; leaflets (5–)9–17(–19), jointed or joint obscure distally. | Astragalus coltonii var. moabensis |