An erect or ascending, amply and diffusely branched shrublet up to ±1 m tall, with slender branches. Young branches sparsely short-pubescent. Leaflets spreading, subulate-acicular, 3-8 mm long, and 0.5-1 mm thick at the base; straight, rigid, subterete-angular, bright green, glabrous, ending in a spinelet up to longer than 1.2 mm. Flowers solitary (or in pairs) on the tips of leafy branches. Bract subulate-acicular, 1.2-2.2 mm long, subglabrous, apical half comprising a spine. Pedicel 0.7-1.7 mm long, short-pubescent. Bracteoles 0.5-1.4 mm long. Calyx tube campanulate, smooth, glabrous; lobes triangular, 2-3 mm long, glabrous, ending in a spinelet more than 1 mm long. Petals partly yellow, partly sombre violet. Standard blade broadly ovate, 6.5-8.5 x 4-5.3 mm, apically slightly incurved, with a blunt tip; back densely white-tomentose-sericeous. Wing blades ovate, 3.4-4.3 x 1.7-2.2 mm, tomentose on lowermost parts. Keel blades lunate, 5-7.3 x 2.5-3.4 mm excluding an apical, linear, 0.6-1.3 mm long process attached just below the keel apex (hence the specific name), upper margin slightly concave, densely tomentose-sericeous on most parts. Pistil pubescent on upper parts of ovary and style base. Pod lanceolate, 10-11.5 x 3.9-4 mm, sparsely sericeous on most parts.
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Diffuse shrublet to 1 m. Leaves 3-foliolate, leaflets awl-shaped, subterete to angular, straight, rigid, spine-tipped, glabrous. Flowers 1 or 2 at branch tips, partly yellow and partly violet, wings shortly hairy, keel silky, with a finger-like process below the apex, calyx glabrous, lobes triangular, spine-tipped, glabrous.