Astragalus preussii
Proc. Amer. Acad. Arts 6: 222. 1864.
Plants sometimes flowering first year, moderate to robust, forming bushy clumps, (10–)12–53 cm, appressed-hairy; from superficial woody caudex. Stems erect or incurved-ascending, diffuse, glabrous or glabrate. Leaves 3.5–15 cm; stipules 2–7 mm, papery at proximal nodes, herbaceous at distal nodes; leaflets (7 or)9–25, blades obovate, suborbiculate, obcordate to oblong, narrowly elliptic, lanceolate, or linear, 6–28 mm, apex retuse-emarginate to rounded, obtuse, acute, or truncate, sometimes apiculate, surfaces glabrous, hairs sometimes on margins or midrib. Peduncles erect-ascending, 2–15 cm. Racemes 3–24-flowered, flowers ascending; axis 1–20 cm in fruit; bracts 1.5–4 mm; bracteoles 2. Pedicels 1–5.5 mm. Flowers 14–24 mm; calyx purple, 6.4–12.3 mm, sparsely strigose, tube 5.1–9.7 mm, lobes subulate, 1.3–2.6 mm; corolla pink-purple, bicolored, or white to pale greenish yellow and, sometimes, modestly suffused with purple; banner recurved through 40–45°; keel (11.1–)11.5–19 mm, apex blunt. Legumes dehiscent on plant, erect to ascending, green or red-dotted becoming stramineous, straight or slightly incurved, cylindroid, ellipsoid, ovoid, or oblong-ellipsoid, inflated, 12–34 × 6–13 mm, unilocular, stiffly papery to leathery, glabrous or puberulent; stipe 0–7 mm. Seeds 20–44.
Distribution
sw United States.
Discussion
Varieties 3 (3 in the flora).
Astragalus preussii was named for Charles Preuss, the topographer with J. C. Frémont on his second expedition in 1843–44, when the type was collected.
Selected References
None.
Lower Taxa
Key
| 1 | Legumes sessile or subsessile; raceme axes 9–19.5 cm in fruit; calyces 6.4–8.5(–9.4) mm; nw Arizona, s Nevada, and sw Utah. | Astragalus preussii var. laxiflorus |
| 1 | Legumes stipitate (stipes 2–7 mm); raceme axes (1–)4–20 cm in fruit; calyces (6.4–)8.5–12.3 mm; n Arizona, se California, s Nevada, and se Utah. | > 2 |
| 2 | Leaflets usually (7–)11–17, blades (2–)5–10 mm wide; nw Arizona, se California, and s Nevada. | Astragalus preussii var. preussii |
| 2 | Leaflets 17–25, blades 1–6 mm wide; nc Arizona, sw Colorado, and se Utah. | Astragalus preussii var. latus |