Astragalus flavus

Title

Astragalus flavus

Authors

Rupert C. Barneby

Scientific Name

Astragalus flavus Nutt.

Description

104. Astragalus flavus

Usually low, wiry, loosely tufted, strigulose nearly throughout with straight, often flattened, appressed, dolabriform hairs up to (0.4) 0.5-0.9 (1.1) mm. long (the calyx sometimes, and even the herbage rarely, pilose-pilosulous with longer, looser, twisted hairs), the herbage cinereous or canescent, rarely greenish, the leaflets often glabrescent medially or quite glabrous above; stems of the year (0.5) 1-20 cm. long, in young plants several, tufted on the root-crown, in older ones numerous, arising from an extensively branching, twiggy caudex, suberect or (when long) decumbent and ascending, mostly simple, or bearing one or more spurs from the lower axils; stipules (2) 3-10 mm. long, all connate-amplexicaul, the lowest (sometimes all) united through nearly their whole length into a bidentate sheath, the median and upper ones commonly united for ± half their length, with erect or spreading blades; leaves (1.5) 3-13 (18) cm. long, all petioled, with (5) 11-19 (21) linear or linear-oblong, rarely oblanceolate, or (in some lower leaves) ovate, obtuse or subacute, usually folded leaflets (3) 6-20 mm. long, the petiole and rachis often stiff, tending to persist on the root-crown or caudex-branches; peduncles stout or quite slender, erect or ascending, (3) 6—23 cm. long; racemes (4) 10-30-flowered, oblong and rather dense at early anthesis, usually elongating, (1) 2-12 cm. long in fruit; bracts scarious with green midrib, or broadly scarious- margined, narrowly ovate to lance-acuminate, (1.5) 2.5—5 mm. long, often reflexed in fruit; pedicels at anthesis very short, subobsolete or up to 0.7 mm. long, in fruit straight, ascending, 1-1.2 mm. long; bracteoles 0; calyx variably pubescent with white or some black hairs, the subsymmetric disc 0.6—1.2 mm. deep, the campanulate tube 3-5.2 mm. long, 2.1-3.8 mm. in diameter, the subulate, lance- subulate, or linear-lanceolate teeth varying from shorter to twice longer than the tube, the whole becoming papery, ruptured, marcescent; petals lemon-yellow, dull straw-yellow, ochroleucous, whitish, or pale lilac, in one var. reddish-lilac, the keel-tip nearly always at least faintly maculate; banner recurved through 45 (90)°, broadly obovate-cuneate to rhombic-oblanceolate, 9-17.8 mm. long, 4.7-8 mm. wide; wings (8.8) 9.3—14.4 mm. long, the claws 2.9—5.1 mm., the oblong- oblanceolate or obliquely obovate, obtuse or subemarginate, slightly incurved blades (6.1) 6.7—10 mm. long, 1.8—3.5 (4.5) mm. wide, the inner margin of the left one infolded over the keel, the right one concave; keel 6.5-10 mm. long, the claws 3-5 (5.3) mm. long, the half-oblong-obovate blades 3.5-5.8 mm. long, 1.8-3 mm. wide, abruptly incurved through 90-100° to the bluntly deltoid apex; anthers (0.45) 0.5—0.7 mm. long; pod erect or ascending at a narrow angle, sessile, oblong- or ovoid-ellipsoid, 7-13 mm. long, 3.5—5 mm. in diameter, straight, a trifle incurved, or rarely a little decurved, rounded at base, contracted distally into a shortly cuspidate beak, dorsiventrally compressed, with flattened or shallowly and openly grooved dorsal face, the lateral angles obtuse, the thick ventral suture prominent but commonly depressed and lying in a double groove formed by incurving (through the pod’s proximal half) of the lateral angles, the somewhat fleshy, green, densely or sometimes thinly strigulose valves becoming leathery or stiffly papery, brownish or stramineous, smooth or faintly cross-reticulate, not inflexed; ovules (6) 8-17; seeds brown or olivaceous, smooth and lustrous, 2-2.5 mm. long.