Astragalus vexilliflexus E.Sheld.
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Authors
Rupert C. Barneby
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Authority
Barneby, Rupert C. 1964. Atlas of North American Astragalus. Mem. New York Bot. Gard. 13(1): 1-596.
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Family
Fabaceae
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Scientific Name
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Type
"Among rocks in the more elevated regions of the Rocky Mountains, Drummond."—Holotypus, K! isotypi, labeled "Drummond, misit Hooker," GH, NY (fragm. in herb. Torr.)!
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Description
Species Description - Low, slender, diffusely bushy-branched, low-tufted, or matted, with a thick, sometimes trunklike woody taproot and at length well-developed, suffruticulose caudex, thinly to quite densely strigulose, strigose-pilosulous, or rarely silky- villosulous with fine, straight or sinuous hairs up to 0.3-0.6 (0.8) mm. long, the herbage green, cinereous, or silvery-canescent, the leaflets often medially glabrescent or glabrous above; stems several or numerous, incurved-ascending, decumbent, or prostrate, 3-25 (30) cm. long, closely leafy, repeatedly branched or at least spurred at all the lower and middle nodes, sometimes throughout, exceptionally simple above the immediate base; stipules 2—5 mm. long, dimorphic, those at the lowest nodes of the year’s growth-cycle amplexicaul and connate into a brownish, firmly papery, truncate or bidentate sheath, the median and upper ones connate through half their length or less, sometimes free nearly to the base, with herbaceous, lance- or deltoid-acuminate free blades; leaves 1-5.5 cm. long, shortly petioled or the uppermost subsessile, with (5) 7—13 commonly crowded, elliptic or linear-elliptic, rarely lanceolate, oblanceolate, or narrowly obovate, flat, folded, or involute leaflets acute at both ends, rarely subobtuse and mucronulate distally, in age dorsally carinate by the prominent, pale midrib; peduncles 0.5 4 cm. long, slender or filiform; racemes loosely 3—7 (ll)-flowered, the flowers at full anthesis spreading from ascending pedicels, the axis 0.5-3 cm. long in fruit; bracts membranous, narrowly lance-acuminate, 1.5—3 mm. long; pedicels filiform or nearly so, at anthesis 1.5—2.5 mm. long, in fruit arched outward or declined, 2-3.5 (4.2) mm. long, tardily disjointing with the calyx and pod; bracteoles 0, exceptionally 1 but minute; calyx 2.4—4.5 mm. long, strigulose or rarely villosulous with white or sometimes partly black hairs, the disc 0.4-0.7 mm. deep, the campanulate or turbinate-campanulate tube 1.4—2.2 mm. long, 1.4—2 mm. in diameter, the subulate, linear-subulate, or subsetaceous teeth (0.8) 1-3 mm. long; petals pink-purple with pale striate eye in the banner, the wing-tips sometimes paler or white, or all lilac, or all but the maculate keel-tip whitish with or without lilac veins in the banner; banner abruptly recurved through ± 90°, broadly ovate- cuneate, notched or emarginate, (4.3) 5.2-9.3 mm. long, 4—6 mm. wide; wings (3.5) 4.4-7.2 mm. long, the claws (0.7) 1.1-2.1 mm., the incurved, obliquely obovate, very obtuse or obscurely emarginate blades of unequal width, the left one broader than the other and concave, its upper margin folded over the keel, the right one plane or nearly so, (3.1) 3.4-5.6 mm. long, 1.5-2.8 mm. wide; keel much shorter than the wings, (2.9) 3.4-5.6 mm. long, the claws (0.9) 1.1-2.1 mm., the obliquely obovate blades abruptly incurved through 100-110° into the bluntly deltoid apex; anthers 0.3-0.4 mm. long; pod loosely deflexed or declined, sessile or nearly so (the stipe, when present, vestigial and not over 0.3 mm. long), the body variable in profile, elliptic, obovate-elliptic, oblong-elliptic, rarely linear- oblong, 4.5-12 mm. long, 1.8-3.5 mm. in diameter, nearly straight but either symmetric or oblique (either the dorsal or the ventral suture then convex and the opposite one nearly straight), commonly cuneate at base, either obtuse and apiculate or acuminate distally, strongly compressed, bicarinate by the slender but salient sutures, the lateral faces at first flat, becoming low-convex as the seeds mature, the thin, green but densely strigulose valves becoming papery and stramineous, not inflexed; ovules (4) 5-8 (11); seeds olivaceous, dark brown, or black, smooth and somewhat lustrous, 1.8-2.7 mm. long.