Astragalus zionis
Proc. Calif. Acad. Sci., ser. 2, 5: 652. 1895.
Plants mat- or tuft-forming, subacaulescent or shortly caulescent, 3–23 cm, densely villous-villosulous or strigulose, hairs basifixed; from branched caudex, sometimes with persistent thatch of leaf bases. Stems prostrate to ascending, 0–11 cm, internodes often concealed by white-hairy stipules and dense white hairs, villous-tomentulose. Leaves 2–15 cm; stipules sometimes shortly connate-sheathing at proximal nodes, 1.5–5.5 mm, submembranous becoming papery-scarious; leaflets 13–25, blades elliptic or ovate, 2–16 mm, apex usually acute, sometimes obtuse, surfaces silvery-villous. Peduncles 0.5–15 cm. Racemes 1–11-flowered, flowers ascending; axis 0.3–6 cm in fruit; bracts 2–5 mm; bracteoles 0–2. Pedicels 1–3 mm. Flowers 18–26 mm; calyx cylindric, 8.3–18 mm, villous, tube 6.5–13.5 mm, lobes subulate, 1.5–5.7 mm; corolla often pink-purple, sometimes pale; banner recurved through 40°; keel concealing style, 14.6–18.6(–19) mm. Legumes ascending, brightly purple-mottled, usually curved, obliquely ovoid-oblong, dorsiventrally compressed, ventrally grooved proximally, 15–35 × 5.5–12 mm, unilocular, fleshy becoming somewhat woody, strigose or villosulous. Seeds 24–30.
Distribution
w United States.
Discussion
Varieties 2 (2 in the flora).
Astragalus zionis is a variable species, consisting of many isolated populations scattered throughout the deeply dissected sandstones of the Colorado Plateau. The connate stipules are anomalous among its close relatives. It is closely related to A. argophyllus, and sometimes differential characters are hard to find. Here it is maintained as a species because the connate stipules and mottled fruits are associated with ecological and distributional patterns.
Selected References
None.
Key
| 1 | Plants mat- or tuft-forming, usually to 2.5 dm wide; legumes 15–25(–28) × 5.5–9 mm; Arizona, Nevada, New Mexico, Utah. | Astragalus zionis var. zionis |
| 1 | Plants mat-forming, often very large, to 10 dm wide; legumes 25–35 × 9–12 mm; Pine Valley Mountains, Utah. | Astragalus zionis var. vigulus |