Astragalus miser var. decumbens

  • Title

    Astragalus miser var. decumbens

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Astragalus miser var. decumbens (Nutt.) Cronquist

  • Description

    49g. Astragalus miser var. decumbens

    Commonly dwarf and densely tufted, the stems 1-15 (22) cm. long; herbage silvery-silky with appressed and often some longer, ascending, straight or nearly straight hairs up to (0.5) 0.6-1 mm. long, the leaflets equally pubescent on both sides; leaves 1.5-9 (12) cm. long, with (7) 9-15 (17) narrowly elliptic to oval- oblanceolate, mostly acute but sometimes obtuse, flat or folded leaflets (2) 4-16 (20) mm. long, the terminal one either contiguous to or remote from, but scarcely longer than the last pair, either decurrent or jointed; racemes (4) 7-14-flowered, the axis little elongating, 1-3 (4) cm. long in fruit; calyx 2.8-4.3 mm. long, the tube 1.8-2.5 mm., the teeth 0.9-1.9 mm., long; petals commonly all purplish, bluish, or tipped with dull purple, sometimes whitish except for the maculate keel- tip; banner 6.9-9.6 mm. long, 5.2-7.4 mm. wide; wings 5.4-7.1 mm. long, the claws 1.5-2.5 mm., the blades 4-5.2 mm. long, (1.4) 1.7-2.5 mm. wide; keel 6.2-7.8 mm. long, the claws 1.5-2.6 mm., the blades 4.9-6 mm. long, 1.8-2.3 mm. wide; pod linear-oblong or -oblanceolate in profile, usually widest a little below the apex but the tip not strongly oblique, straight or obscurely sigmoid, (1.2) 1.4-2.1 cm. long, 2.2-3.3 mm. in diameter, the densely strigulose valves faintly mottled; ovules 12-18.—Collections: 31 (vi); representative: C. L. Hitchcock 16,558, 16,626 (NY, RSA, WS); Ripley & Barneby 7945 (CAS, RSA, UTC); L. & R. Williams 3145 (NY, WS, WTU); C. L. Porter 5372 (NY, RM); Merrill & Wilcox 537, 585 (NY).

    Dry gravelly clay banks, hillsides, bluffs, and gullied knolls, commonly among sagebrush at 3700-7600 feet, ascending in the Big Horn Mountains on stony meadows up to 9600 feet, without apparent rock preference although most abundant on sedimentary formations, locally plentiful in the foothills of western Wyoming, from the upper Green River Valley and the west affluents of the North Platte, north through the Wind, Big Horn, and Powder Valleys to the upper Yellowstone River in southcentral Montana.—Map No. 21.—Mid-May to August.

    Astragalus miser var. decumbens (Nutt.) Cron. in Leafl. West. Bot. 7: 18. 1953, based on Homalobus decumbens (reclining) Nutt. ex T. & G., Fl. N. Amer. 1: 352. 1838.—"Sandy plains of the Colorado of the West, near the sources of the Platte... Nuttall."—Holotypus, labeled by Nuttall "Homalobus * decumbens. R. Mts. Platte," BM! isotypi, GH, K, NY, PH!

    Astragalus decumbens (Nutt.) Gray in Proc. Amer. Acad. 6: 229. 1864. Tragacantha decumbens (Nutt.) O. Kze., Rev. Gen. 944. 1891. Phaca decumbens (Nutt.) Piper in Contrib. U. S. Nat. Herb. 11 (Fl. Wash.): 373. 1906. Astragalus campestris var. decumbens (Nutt.) Jones, Rev. Astrag. 74. 1923. A. decumbens var. decumbens Cron. in Leafl. West. Bot. 3: 251. 1943, pro parte.

    Phaca parvifolia (small-leaved) Nutt. ex T. & G., Fl. N. Amer. 1: 348. 1838.—"Rocky Mountains towards the sources of the Platte."—Holotypus, labeled by Nuttall "Phaca *parvi- folia. R. Mts.," BM!—The spm. at PH, labeled by Nuttall "Astragalus *parvifolius. Missouri." = A. gracilis Nutt., q. v.

    Astragalus divergens (bending outward) Blank. in Mont. Agr. Coll. Sci. Stud. 1: 73, Pl. II, 1905 (feb.).—"... near Big Coulee creek, about 30 miles northeast of Big Timber, Sweet Grass county, June 15, 1902."—No typus examined, but the description, excellent accompanying illustration, and Rydberg’s identification of H. camporum with it, are decisive.—Homalobus divergens (Blank.) Rydb. in Bull. Torr. Club 34 : 417. 1907.

    Homalobus camporum (of the plains) Rydb. in Bull. Torr. Club 32: 666. 1905 (dec.).— "Wyoming: Bush Ranch, Sweetwater Co., June 10, 1900, Aven Nelson 7085."—Holotypus, from "summit of Steamboat Mountain," NY!

    On account of its ordinarily pink-purple flowers, var. decumbens is the most handsome of the malpighian-haired forms of weedy milk-vetch. It is locally abundant in western Wyoming, sometimes found in such numbers as to lay down a roseate carpet of blossoms over stony gaps between clumps of sagebrush, lupine, and Wyethia. There are, however, whole populations, especially prevalent in the Big Horn Valley, in which only the keel-tip is stained with color, the other petals being whitish or almost pure white turning straw-color on drying. Such plants closely resemble var. praeteritus, differing only in having leaflets on the average (and for the most part absolutely) broader and in the higher ovule-number.