Astragalus Mulfordae

  • Title

    Astragalus Mulfordae

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Astragalus mulfordiae M.E.Jones

  • Description

    135. Astragalus Mulfordae

    Low, slender, commonly sparsely leafy, with a taproot and at length loosely forking, suffruticulose caudex, thinly strigulose with fine, straight, appressed or subappressed hairs up to 0.2—0.5 mm. long, the herbage green or yellowish-green, the leaflets glabrous above; stems several or numerous, diffuse and ascending, 1-2.5 dm. long, simple or branched at 1-2 nodes preceding the first peduncle; stipules 1.5-5 (6) mm. long, dimorphic, the lowest amplexicaul and connate into a papery-scarious, bidentate sheath, the upper ones semiamplexicaul, free, with triangular or lanceolate, erect or deflexed blades; leaves (2.5) 4.5-10.5 cm. long, shortly petioled, with very slender, stiff and commonly subpersistent rachis and (7) 15-25 distant, often scattered, linear-oblong,-oblanceolate, or filiform, obtuse or subacute, mostly folded leaflets 1-11 mm. long, the terminal one of at least some upper leaves continuous with the rachis, rarely all jointed like the lateral ones; peduncles (0.5) 1.5-7 cm. long, usually much shorter than the leaf; racemes loosely and often remotely (5) 8-19-flowered, the flowers early declined, the axis incurved-ascending, (2) 3-10 cm. long in fruit; bracts membranous, ovate or lance-ovate, 0.7-2 mm. long; pedicels 0.7-2 mm. long, at anthesis ascending, in fruit arched outward but scarcely elongating; bracteoles 0-2; calyx 2.8-5 mm. long, strigulose with white, white and fuscous, partly black, or wholly black hairs, the disc 0.5-1 mm. deep, the campanulate tube 1.8-3 mm. long, 1.5-2.4 mm. in diameter, the subulate teeth 0.8-2 mm. long, the whole becoming papery, marcescent unruptured; petals white or whitish, drying yellowish, the banner sometimes brownish-striate; banner abruptly recurved through (50) 85-100°, ovate- or obovate-cuneate, notched, 6.2-8.2 mm. long, 4.5-5.2 mm. wide; wings 6.2-8.1 mm. long, the claws 2.4—2.7 mm., the obliquely obovate-elliptic, obtuse blades 4.2-5.8 mm. long, 2-2.7 mm. wide; keel 4.7—5.7 mm. long, the claws 2.3-2.7 mm., the half-circular blades 2.4—3.3 mm. long, 1.8—2.5 mm. wide, incurved through 115-130° to the deltoid, often slightly porrect and then sharply deltoid apex; anthers 0.3-0.5 mm. long; pod pendulous, stipitate, the stipe 3-5 mm. long, the lunately half-ellipsoid, gently incurved body (9) 10-16 mm. long, 3.2-4.5 mm. in diameter, cuneate at both ends, cuspidate at apex, triquetrously compressed, carinate ventrally by the suture, the lateral angles narrow but obtuse, the lateral faces nearly plane, the dorsal one depressed and openly sulcate, the thin, pale green, finely strigulose valves becoming papery, stramineous, somewhat lustrous, delicately cross-reticulate, inflexed as a complete septum 1.3—2 mm. wide; ovules 11-16; seeds brown or greenish-brown, smooth but dull, 2-2.6 mm. long.—Collections: 11 (i); representative: Christ & Ward 6989 (ID, NY), Jones 6239 (NY, POM, WS); Ripley & Barneby 6134 (CAS, IDS, NY, RSA); Maguire & Holmgren 26,227 (NY, UTC).

    Sandy bluffs and dunelike talus in the foothills, about 2200—2800 feet, local but forming colonies, along and near the Snake and Boise Rivers and tributary creeks, about the west end of the Snake River Plains, in Ada, Washington, an Owyhee Counties, Idaho, and along the lower Owyhee River in extreme eastern Malheur County, Oregon.—Map No. 53.—May and June.

    Astragalus Mulfordae (A. Isabel Mulford, student of Aloe, collected in s. Idaho in summer of 1892) Jones, Contrib. West. Bot. 8: 18. 1898.—"Boise City, Idaho, June 7th, 1892, A. Isabel Mulford."—Holotyus, MO! isotypus, NY!—Onix Mulfordae (Jones) Rydb. in Bull. Torr. Club 40: 51. 1913.

    The elegantly pretty Mulford milk-vetch is easily picked out from among species of the Intermountain States with small, whitish flowers and may be recognized by its combination of lower stipules connate into a scarious sheath with a pod pendulous, stipitate, and almost exactly triquetrous, the three faces being of almost equal width. The pod is sometimes a trifle turgid, and the papery valves become straw-colored and shiny in ripening. Care must be taken, however, to distinguish A. oniciformis of the preceding section, a plant very similar in general habit but more densely and loosely pubescent, and with none of the stipules connate. The Mulford milk-vetch is rather local and variable only in a few features. The populations, perhaps but one, found near Boise City have about 15-21 linear-oblanceolate leaflets, of which the terminal one is continuous with the rachis in only a few leaves of some plants; and the flowers are here comparatively large, with calyx about 4.5-5 mm. and banner about 8 mm. long. The commoner form of the species from sandy bluffs along the Snake River and tributary canyons differs slightly in having leaflets mostly 19-25 in number, mostly linear or filiform, the terminal one almost always decurrent in the upper leaves, and flowers on the average a trifle smaller, with calyx about 4-5 mm. and banner 6-8 mm. (but only rarely 8 mm.) long. Whether these recorded differences are significant of racial modification or have been brought out accidentally by faulty sampling from too few colonies of plants remains a problem for future study.