Climbers, perennial, herbaceous, from a stout rootstock. Stems (1-)2-8 m, thin, sulcate, branched and leafy throughout. Petiole 0.5-3 cm; leaf blade glaucous abaxially, with 1 pair of usually alternate pinnae; rachis ending in a thin branched cirrose tendril; leaflets twice (rarely to 3 ×) ternately compound; ultimate leaflets ovate, 10-25 × 7-20 mm, margin entire, apex obtuse with small mucro. Raceme 1-3 cm, 6-14-flowered, obliquely nutant; peduncle 2-4 cm; bracts linear to narrowly oblanceolate, 3-10 × 1-2 mm, margin entire, apex acute. Pedicel thin, reflexed at base, 10-20 mm, elongating in fruit to 30 mm. Sepals 3-4 × ca. 2 mm, abruptly tapering from a broad base, slightly dentate. Corolla yellow, sometimes with reddish tips, flattened, oblong-cordate to subtriangular in profile, 18-20 × 8-11 mm; outer petals saccate, sharply keeled, at base often narrowly winged; sinus at petiole insertion ca. 3 mm deep; dorsal crest of inner petals overtopping petal apex ca. 2 mm; nectary sharply bent forward in distal 1/3, tapering to slender curved apex. Stigma almost square, slightly notched at apex, with small papillae in forward corners and more prominent rounded papillae in basal corners. Capsule tapering to both ends, flattened, with a narrow marginal wing, 20-25 × 4-5 mm, tipped by style 5-6 mm. Seeds black, rounded-ellipsoid, 1.7-2 mm, with rather small elaiosome. Fl. Aug, fr. Sep.
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