Astragalus xiphoides

Title

Astragalus xiphoides

Authors

Rupert C. Barneby

Scientific Name

Astragalus xiphoides (Barneby) Barneby

Description

53. Astragalus xiphoides

Slender, sparsely leafy or apparently leafless, strigulose-cinereous with fine, straight, appressed hairs up to 0.3-0.5 mm. long; stems few, 3-4.5 dm. long, diffuse and weakly ascending, subterranean for a space of 2-6 cm., branched at the first 2-3 nodes above ground and the more robust branches often again branched, floriferous upward from near or well below the middle, the first 1-2 fertile nodes sometimes bearing paired peduncles of unequal length; stipules 2-7 mm. long, the lowest ones large, ovate, obtuse, several-nerved, early becoming papery, decurrent-amplexicaul around half to nearly the whole stem’s circumference, the median and upper ones smaller, firm, triangular or broadly lanceolate, erect; leaves 2.5-13 cm. long, either all reduced to the linear-filiform or sometimes apically dilated and recurved rachis, or some of them bearing 1-2 (3) pairs of scattered, linear-involute, decurrent leaflets 3—17 mm. long; peduncles ascending, 3.5-7.5 cm. long, the early ones stout, the uppermost slender or filiform, all shorter than the leaf; racemes loosely or remotely (3) 7-17 (35)-flowered, secund or becoming so, the axis elongating and (2) 4—18 (33) cm. long in fruit; bracts firm, triangular-lanceolate, 1.2—2.6 mm. long; pedicels slender, at anthesis ascending and gently arched outward, 2—4.5 mm. long, in fruit horizontally spreading from the twisted base, loosely recurved, or abruptly refracted, somewhat thickened, 5-8 mm. long; bracteoles 0-2; calyx 4.6-6 mm. long, white-strigulose, the scarcely oblique disc 0.6-0.8 mm. deep, the campanulate tube 3.8-4.1 mm. long, ± 2.8 mm. in diameter, the subulate or triangular-subulate teeth 0.8-1.9 mm. long; petals ochroleucous, immaculate, little or somewhat irregularly graduated, all very strongly incurved; banner ovate-cuneate, emarginate, or entire and obscurely acuminate at apex, ± 9 mm. long, 4.6—6 mm. wide; wings (as long or a trifle longer) 8.9-9.3 mm. long, the claws 3.6-3.8 mm., the lunately oblong-elliptic, obtuse, strongly incurved blades 6-6.3 mm. long, 2.5 mm. wide; keel ± 8 mm. long, the claws 3.6-3.8 mm., the lunately half-obovate blades 4.7-5 mm. long, 2.6-2.1 mm. wide; pod declined or pendulous, sessile, narrowly lance-oblong in profile, straight or nearly so, 2.5-3.7 (4) cm. long, 4—5.5 mm. in diameter, cuneate at both ends but more broadly so at base, shortly cuspidate at apex, strongly compressed, bi- carinate by the filiform sutures, the faces flat or nearly so, the thin, pale green but densely strigulose valves becoming papery and stramineous; ovules 14-18; seeds brown, smooth but dull, 2.5-3 mm. long.—Collections: 4 (i); representative: Wiegand & Upton 3618 (MO); Goodding 4-45 (ARIZ); Hough 37 (US).