Astragalus oniciformis

Title

Astragalus oniciformis

Authors

Rupert C. Barneby

Scientific Name

Astragalus oniciformis Barneby

Description

131. Astragalus oniciformis

Slender but wiry, diffuse, perennial, with a taproot and at length loosely forking, suffruticulose caudex, loosely strigulose or subvillosulous with incumbent or ascending, nearly straight or sinuous hairs up to 0.35-0.5 (0.6) mm. long, the herbage greenish-cinereous, the leaflets glabrous or medially glabrescent above; stems several or numerous, decumbent or prostrate, (0.5) 1-2.5 dm. long, commonly spurred at the lowest nodes and thence floriferous upward from all succeeding axils; stipules papery-membranous or early becoming so, 1.5-3.5 (4) mm. long, triangular or triangular-acuminate, decurrent around half, or the lowest around the whole stem’s circumference but not connate; leaves 2.5-1.5 cm. long, shortly petioled or the upper ones subsessile, with stiff but slender rachis and (13) 17—25 (27) rather distant, scattered, narrowly to broadly elliptic, oval, or oblong, obtuse or retuse, mostly folded leaflets 1-6.5 mm. long; peduncles 0.5-2.5 cm. long, much shorter than the leaves; racemes very loosely (4) 6-12-flowered, the flowers early nodding, the axis becoming 1-7 cm. long in fruit, usually produced beyond the last flower as a subulate appendage; bracts papery-membranous, ovate or lanceolate, 0.5-1.8 mm. long; pedicels filiform, very early arched outward or ultimately recurved, at anthesis 1-1.4 mm., in fruit 1-1.6 mm. long, tardily disjointing with the fruit; bracteoles 0; calyx 2.9-3.8 mm. long, strigulose-villosulous like the herbage with white or some dark hairs, the subsymmetric disc 0.6 mm. deep, the campanulate tube 2.1-2.3 mm. long, 1.7-2 mm. in diameter, the subulate teeth 0.8-1.5 mm. long, the whole becoming papery, marcescent unruptured; petals ochroleucous, the banner veined with dull brownish-lilac; banner abruptly recurved through 90° or sometimes further, broadly obovate-cuneate, 5.3-6.8 mm. long, 4-5.4 mm. wide; wings (0.7 mm. longer to 0.7 mm. shorter than the banner) 5.7-6.8 mm. long, the claws 2-2.5 mm., the oblong-obovate, obtuse blades 4-4.4 mm. long, 1.9-2.9 mm. wide, both incurved but the left one further and more abruptly than the right; keel 4-5 mm. long, the claws 1.8-2.3 mm., the halfcircular blades 2.4—3 mm. long, 1.7-1.9 mm. wide, abruptly incurved through 110-130° to the deltoid, often obscurely porrect apex; anthers 0.35-0.5 mm. long; pod pendulous, stipitate, the stipe (1.5) 2—4 mm. long, the body lance- or oblong- ellipsoid, usually a trifle incurved, 7-12 mm. long, (2) 2.5-3.5 (3.8) mm. in diameter, cuneate at both ends or truncately contracted at base into the stipe, cuspidate at apex, triquetrously compressed with nearly flat lateral and openly sulcate dorsal faces, keeled ventrally by the prominent suture, the thin, green but rather densely strigulose valves becoming papery, stramineous, delicately cross- reticulate, inflexed as a not quite complete septum 0.7-1.2 mm. wide; dehiscence apical and through the ventral suture; ovules 6-12; seeds brown or greenish-brown, sometimes purple-speckled, smooth but dull, 1.5-1.8 mm. long.—Collections: 4 (i); representative: Nelson & Macbride 2987 (CAS, GH, MO, NY); R. J. Davis 3088 (IDS).