Astragalus pachypus

  • Title

    Astragalus pachypus

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Astragalus pachypus Greene

  • Description

    144. Astragalus pachypus

    Handsome, commonly robust, rather rigid, sparsely leafy, bushy-branched, strigulose nearly throughout with appressed, filiform or mostly flattened and scalelike hairs up to 0.4-0.6 (0.7) mm. long, the stems and usually the upper surface of the leaflets very densely so, silvery-white, the leaflets more thinly pubescent beneath, greenish or cinerous; stems several or numerous, erect and ascending m clumps (rarely decumbent and trailing on steep banks), usually stout and striate, (1.5) 2-5.5 (8) dm. long, simple or branched at either 1-3 nodes preceding the first peduncle, or at base only, flexuous and often abruptly zigzag distally, stipues 1.5-5.5 mm. long, decurrent around about half the stem’s circumference, the short, deltoid or deltoid-acuminate, erect or deflexed blades mostly shorter than their wide bases, glabrate dorsally or at least less densely pubescent than the stems, forming a contrasting yellowish spot at each node, ultimately papery and deciduous, the margins beset with a few clavate processes; leaves (2.5) 5—15 (16.5) cm. long, shortly petioled or the uppermost subsessile, with stiff, often long-persistent rachis and 11-27 rather distant, linear or linear-oblong, retuse, truncate-emarginate, or exceptionally subacute, at least marginally involute, thick-textured leaflets (3) 5-23 (34) mm. long; peduncles stout, stiffly erect, (0.5) 0.7-2 dm long, nearly always surpassing the leaves; racemes loosely (4) 5-20 (28)-flowered, the axis (2) 3-13 cm. long in fruit; bracts scarious, ovate or ovate-acuminate, 0.7-2.5 mm. long; pedicels ascending, stout, straight or nearly so, at anthesis 0.9-3 mm., in fruit thickened and 1.5-5.5 mm. long; bracteoles 2, minute, rarely 0; calyx 5.5-9.5 mm. long, strigulose with black, mixed black and white, or rarely all white hairs, the slightly oblique disc 1.1-1.8 mm. deep, the broadly campanulate tube 3.6-5.2 mm. long, 3.6-5 mm. in diameter, the broadly subulate teeth (1.5) 1.8-4.3 mm. long; petals clear white, sometimes pink- or lavender-tinged, or lemon-yellow; banner at full anthesis recurved through about 45°, sometimes further in withering, broadly rhombic-ovate or -elliptic, shallowly or deeply notched, 15-22 mm. long; wings 14-18 mm. long, the oblong-oblanceolate or narrowly oblanceolate, obtuse or obscurely emarginate, gently incurved blades 7.2-13 mm. long, their inner margins more or less involute or crimped; keel 10.7-15.3 mm. long, the lunately half-elliptic blades 6.7-10.3 mm. long, 2.7-4.2 mm. wide, rather gently incurved through 50-95° to the triangular, ultimately obtuse, often obscurely porrect apex; stipe of the pod stout, straight, horizontally spreading or ascending at a wide angle, 4-8 mm. long, the body lunately or falcately oblong-cylindric, incurved to the perpendicular or nearly so, (1.2) 1.5-2.5 (2.8) cm. long, 4-7.5 mm. in diameter, cune- ately contracted at base, and at apex into a short, rigid cusp, when first formed terete, solid, fleshy, becoming strongly compressed laterally when ripe, the prominent, thick, cordlike sutures then salient, the lateral faces low-convex, the green, glabrous, lustrous valves becoming stiffly leathery or subligneous, stramineous or brownish, both transversely reticulate and wrinkled lengthwise, the septum (2.7)3.5-6 mm. wide, complete below the unilocular beak; seeds brown, greenish-brown and purple-dotted, rarely blackish-purple, punctate but somewhat lustrous, 3.1-4.6 mm. long.