Astragalus holmgreniorum
Brittonia 32: 24, fig. 1. 1980.
Plants acaulescent, 4–12 cm, loosely pilosulous; from thickened, superficial root-crown. Stems essentially absent. Leaves 4–21.5 cm; stipules 2.5–8 mm, papery; leaflets (5–)9–15(or 17), blades broadly obovate to obcordate, 6–16 mm, apex emarginate, surfaces loosely pilose abaxially, glabrous adaxially. Peduncles procumbent, 2–9 cm, shorter than leaves. Racemes 4–16-flowered, flowers ascending to spreading; axis 0.4–6.5 cm in fruit; bracts 4+ mm. Pedicels 1–2 mm. Flowers 18–23.5 mm; calyx cylindric, 10.5–12.5 mm, sparsely white-pilose, tube 8–9.5 mm, lobes subulate, 2–3.5 mm; corolla pink-purple; keel 16.5–18.5 mm. Legumes reclined (humistrate), green or purplish becoming stramineous or brownish, lunately incurved, ellipsoid, 3-sided compressed, 2.5–5.5 × 6–9 mm, bilocular, leathery, glabrous. Seeds 30–34. 2n = 22.
Phenology: Flowering Apr–Jun.
Habitat: Warm desert shrub (Larrea) community.
Elevation: 800–900 m.
Discussion
Astragalus holmgreniorum has a narrow distribution along the Virgin River in St. George County in Utah and adjacent Mohave County in Arizona.
Long known from collections, Astragalus holmgreniorum was only recently described. It is apparently the historical basis of reports of A. tephrodes from Utah (R. C. Barneby 1989). At the time of description, Barneby placed A. holmgreniorum within sect. Argophylli, but its curved, three-sided, bilocular fruits are similar in fundamental details to those within sect. Malaci, where it is here allied.
Astragalus holmgreniorum is in the Center for Plant Conservation’s National Collection of Endangered Plants.
Selected References
None.