Astragalus striatiflorus

Welsh, S. L., Atwood, N. D., Goodrich, S., & Higgins, L. C. (2015). A Utah flora (No. Ed. 5). Brigham Young University.

 

Astragalus striatiflorus M. E. Jones, Proc. Calif. Acad. Sci. II. 7: 643. 1895. [Type: Utah, Washington Co.?: above Springdale, in red sand, M.E. Jones 6080k, 25 Sept. 1894, holotype POM!]

Escarpment milkvetch

Perennial, subacaulescent to short-caulescent, 1.5-6 cm tall, radiating from a simple superficial or more commonly branching subterranean caudex and ultimately stout taproot; pubescence basifixed; stems buried for (0) 1–30 cm or more, 0–5 cm long, only the tips produced above the sand; stipules 2–4 mm long, all connate-sheathing, obscuring the stem or nearly so; leaves 1–4 cm long; leaflets 5–13, 1–7 mm long, 0.8–2.5 mm wide, ovate to obovate or oblanceolate, obtuse, mucronate, or emarginate, pilosulous; peduncles 1–3 cm long; racemes 2–5-flowered, the flowers ascending at anthesis, the axis 0.2–1 cm long; pedicels 1–1.5 mm long; bracteoles 0; calyx 5.5–7 mm long, the tube 3–4 mm long, campanulate, hirsutulous, the teeth 1.8–3 mm long, subulate; flowers 9–12 mm long, pink-purple or whitish and commonly suffused with purple, the keel-tip purple, long-attenuated, with the capitate stigma protruding; pods spreading, sessile, the body bladdery-inflated, ellipsoid, 12–18 mm long, 8–15 mm wide (when pressed), mottled, spreading- hairy, bilocular. Interdune valleys, sandy depressions on ledges, and bars and terraces in stream channels, in pinyon-juniper, ponderosa pine, and sandy desert shrub communities, at 1500 to 2000 m in Kane (from the Paria River westward to the Coral Pink Dunes vicinity) and e. Washington cos.; Coconino Co.; Ariz.; a Dixie Divide endemic; 24 (xiv).

The psammophilous, escarpment milkvetch is a singular plant, resembling the montane A. perianus more closely than any other in Utah. The attenuated keel- tip, protruding stigma, and inflated, bilocular pods are both unusual and diagnostic features. Distribution is almost exclusively in Kane County, Utah and adjacent Coconino County, Arizona.

The Escarpment milkvetch is not known from contemporary collections near Springdale, and the report of the type specimen taken exceptionally late in the season in Washington County in flower only is perhaps due to a mislabeled specimen, or possibly it came from a disjunct population in Zion Canyon not subsequently discovered. Jones’ published itinerary (Munz
1965) shows him traveling from Caanan Ranch, west of Pipe Springs, Mohave Co., Arizona to Zion Canyon on 25 September 1894, with the collection number cited as type (6080k) taken “above Springdale,” but probably some distance away prior to his arrival there, more likely in western
Kane County, Utah, although the altitude recorded by Jones is too low for either of those areas by a couple of thousand feet. Possibly it still exists somewhere in Zion Canyon.