Astragalus duchesnensis

Title

Astragalus duchesnensis

Author(s)

Rupert C. Barneby

Scientific Name

Astragalus duchesnensis M.E.Jones

Description

59. Astragalus duchesnensis

Wiry, sparsely leafy, strigulose throughout or nearly so with fine, straight, appressed (sometimes a few narrowly ascending) hairs up to 0.3-0.55 mm. long, the stems and herbage greenish or cinereous, the leaflets either pubescent on both sides or commonly glabrescent above; stems few or several, sometimes solitary, erect and ascending in clumps or sometimes diffuse and straggling, 1.5—3.5 dm. long, subterranean for a space of 1.5—6 cm., leafless and purple-tinged toward the base, branched or spurred at 1—5 nodes preceding the first peduncle, the branches sometimes again branched, becoming zigzag distally; stipules dimorphic, the lowest ones ovate-oblong, papery-membranous, pallid or brownish, several-nerved, 3-8 mm. long, adnate to the vestigial petiole and amplexicaul-decurrent around 3/4 to the whole stem’s circumference, free, the median and upper ones smaller, triangular or triangular-acuminate, the firm, green or purplish blades erect or recurved; leaves (1.5) 2.5-9.5 cm. long, shortly petioled, with 7-11 (15) rather distant, linear, linear-filiform, or (in some lower leaves) narrowly oblanceolate, obtuse or retuse, involute or rarely flat, petiolulate leaflets 3—20 mm. long, but the leaflets of the uppermost leaves often reduced in size, or number, or absent, the terminal one represented by a scarcely expanded, often falcate blade continuous with the rachis; peduncles erect or incurved-ascending, (3) 4-9.5 cm. long; racemes loosely (3) 6-18 (22)-flowered, the axis becoming (1) 2.5-12 cm. long in fruit; bracts papery or early becoming so, triangular-ovate or lance-acuminate, 0.7-2 mm. long; pedicels at anthesis straight, ascending, 0.8-1.4 mm. long, in fruit arched outward or abruptly downward, thickened, 1-2.2 mm. long; bracteoles 0; calyx 3.6-5 mm. long, strigulose with black or mixed black and white hairs, the oblique or symmetric disc 0.7-1.2 mm. deep, the campanulate, often purplish tube 3.1-4.3 mm. long, 2.3-2.9 mm. in diameter, the broadly triangular-subulate or deltoid teeth 0.4-1 mm. long; petals bicolored, the pale-eyed banner and keel reddish-pink or -purple, the wings white; banner ovate-cuneate, shallowly emarginate, 8.5-12.4 mm. long, 5.2-7.8 mm. wide; wings (about as long or a trifle longer) 8.4-12.5 mm. long, the claws 4-5.2 mm., the oblong-oblanceolate, obtuse, slightly incurved blades 5-8.6 mm. long, 1.8-2.8 mm. wide; keel 8-9.8 mm. long, the claws 3.6-4.8 mm., the half-obovate blades 4.5-5.9 mm. long, 2.4-3.1 mm. wide, incurved through 90-95° to the broadly deltoid, obtuse apex; anthers 0.4-0.75 mm. long; pod deflexed, sessile or attenuate at base into a thick, glabrous, stipelike neck up to 1 mm. long, the body linear or commonly linear-oblanceolate in profile, 2-3.5 cm. long, 3.3-5.3 mm. in diameter, straight or more often gently arched downward in the lower 1/3 and straight or nearly so thereafter, tapering into the narrow base, triangular-cuspidate at apex, dorsiventrally compressed in the lower 1/2 and there obscurely trigonous, with flattened or openly and shallowly grooved dorsal and low-convex lateral faces, becoming ± laterally compressed and 2-sided distally, carinate ventrally by the prominent suture, the thinly fleshy, pale green or purplish, densely strigulose valves becoming stiffly papery and stramineous; ovules 21-31; seeds olivaceous or drab, closely pitted, 2.1-3 mm. long.—Collections: 12 (v); representative: Ripley & Barneby 8714 (CAS, RSA, UTC); W. A. Weber 5313 (COLO, RSA); Rollins 1743 (NY); Barneby 12,706 (CAS, NY, RSA).