A sprawling subherbaceous or suffruticose annual, the branchlets slender, spar-ingly to heavily hirsute, sparingly to moderately recurved-aculeate. Leaves mod-erately small, bipinnate, the pinnae a single pair, the leaflets only 2 pairs per pinna; petiole slender, 15-40 mm. long, sparingly armed or unarmed, eglandular; pinnular axis very short, seldom 5 mm. long; leaflets asymmetrically obovate to oblong, usually broadest above the middle, up to 2 cm. long and 4-7 mm. wide, the inner member of the basal pair very reduced, usually obtuse or rounded and briefly mucronate apically, obliquely rounded basally, strigose-pubescent on both upper and (more heavily) lower surface, the venation prominent below; stipules linear, about 4 mm. long, pectinate-ciliate. Inflorescence of axillary, pedunculate heads, racemose terminally because of non-foliate nodes; peduncles up to 3 cm. long, sub-glabrous; heads dense, globular; floral bractlets linear-lanceolate, 1-2 mm. long, pectinate-ciliate. Flowers small, sessile, pinkish-white?; calyx campanulate, minute; corolla funnelform, about 2 mm. long, membranous, usually puberulent apically, 4-(5?)-lobed, the lobes less than half as long as the tube; stamens 4 (5?), about 6 mm. long, glabrous, the anthers orbicular; ovary subglabrous. Legume oblong, mostly 1-1.5 cm. long and 3-5 mm. wide, flat, few-segmented, the persistent margins heavily setose-spinose, the valves less heavily so.
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