Astragalus flavus var. argillosus

  • Title

    Astragalus flavus var. argillosus

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Astragalus flavus var. argillosus (M.E.Jones) Barneby

  • Description

    104c. Astragalus flavus var. argillosus

    Habit of var. candicans and differing appreciably only in the slightly smaller, purple flowers, and elongate, hirsute calyx-teeth; herbage commonly strigulose, sometimes also pilose with some longer, ascending hairs up to 1-1.5 mm. long; pod small, ± 7-10 mm. long; ovules 8—11.—Collections: 9 (i); representative: Jones (from San Rafael Swell) in 1914 (CAS, DS, NY); Holmgren & al. 7765 (CAS, UTC, WS); Ripley & Barneby 8677 (CAS, RSA).

    Gravelly clay flats, sandy banks, and desert washes, in alkaline soils derived from sandstone, 4000-4900 feet, locally plentiful in the Colorado Basin south of Tavaputs Escarpment, on the Price, San Rafael, Green, and Grand Rivers in Emery, Wayne, and Grand Counties, Utah.—Map No. 43.—Late April to July.

    Astragalus flavus var. argillosus (Jones), stat. nov., based on A. argillosus (of clay soil) Jones in Zoë 2: 241. 1891.—"May 9, 1890, at Green River, Utah ... "—No spm. at POM bears the published data. Lectotypus, collected by Jones at Green River, May 6, 1891, POM (3 sheets)! paratypi, collected at the same place on May 7, 1891, POM, WS!—Cnemidophacos argillosus (Jones) Rydb. in Bull. Torr. Club 40: 52. 1913.

    The present variety agrees closely with var. candicans in growth-habit, shape and size of the petals, and small, relatively few-ovulate pod; it seems to differ from A. flavus as understood by Jones (his A. confertiflorus) only in the characters of calyx and flower-color already stressed in the varietal key. The calyx-teeth were described by Jones as reaching a length of 9 mm ; I have found none over 6 mm. long in his material, and they are quite variable in the type-region, sometimes as little as 3 mm. long. Since there are examples of calyx-teeth up to 4 mm. long in var. flavus, and forms of var. candicans with purplish flowers, the long, spreading, basifixed trichomes on the calyx of var. argillosus are evidently its only unique feature. Therefore it is no longer possible to accept A. argillosus as a distinct species. The dispersal area of var. argillosus fits in neatly between those of var. flavus and var. candicans and is what one might predict for a geographic subspecies.