Astragalus Robbinsii var. alpiniformis

  • Title

    Astragalus Robbinsii var. alpiniformis

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Astragalus robbinsii var. alpiniformis (Rydb.) Barneby

  • Description

    7c. Astragalus Robbinsii var. alpiniformis

    Closely resembling the more slender, diffuse forms of var. Blakei, except as follows: leaflets 9-17, ovate to obovate or lance-elliptic, mostly emarginate, (3) 5-12 mm. long; stipe of the pod 1.2-2 mm. long, the rather broadly ellipsoid body 8-13 mm. long, 3.7-5 mm. in diameter, the apical cusp 0.7-2.2 mm. long, the valves strigulose with black, largely black, rarely all white hairs 0.1—0.35 mm. long; ovules 3-6.—Collections: 5 (o); representative: Maguire & Holmgren 26,688 (GH, NY, RSA, UTC, WS), 27,037 (NY, RSA, UTC); Peck 22,499 (WILLU).

    Brushy or shingly stream banks and gravel bars, sometimes inundated by spring freshets, on granite, from 4200 upward to ±7000 feet along Hurricane Creek, Wallowa Mountains, Oregon.—Map No. 5.—June to August.

    Astragalus Robbinsii var. alpiniformis (Rydb.) Barneby ap. Hitchc. & al. in Univ. Wash. Pub. Biol. 17: 258. 1961, based on Atelophragma alpiniforme (resembling A. alpinus) Rydb. in Bull. Torr. Club 55: 129. 1928.—"On bars of Hurricane Creek. Wallowa Mountains, Oregon, August 25, 1898, Cusick 2103."—Holotypus, GH! isotypi, G, K. MINN. MO. ND. ORE, P. US, WS!—A. alpinus var. alpiniformis (Rydb.) Peck, Man. Pl. Ore. 447. 1940.

    The var. alpiniformis resembles var. occidentalis in its short, shortly stipitate pod. differing in its more numerous and relatively small leaflets. The few ovules constitute its best differential character. The variety is probably not directly related to or derived from var. occidentalis but may have arisen as a parallel mutation from var. minor and is only assured an independent existence through its isolation in the Wallowa Mountains. The collections of var. minor from stations nearest to Hurricane Creek in Idaho show no sign of passage toward var. alpiniformis.

    In its riparian habitat, apparently quite similar to that of var. Jesupi along the Connecticut River in New England, var. alpiniformis is subjected to flooding during the spring thaw, and the plants are sometimes partly buried under mobile shingle. The subterranean root-crown in such plants might suggest A. alpinus, but the resemblance is purely fortuitous.