Herbs, perennial, suffrutescent, 1-3 m tall. Branches terete, slightly with greenish white striations, often with small sparse flattened prickles. Stipules linear-lanceolate, ca. 7 × 1 mm, caducous, glabrous, apex acuminate. Leaves 40-80-foliolate; rachis 13-30 cm, abaxially with sparse prickles, adaxially grooved; stipels acerose, slender; leaflet blades linear-oblong, 10-16 × 2-3 mm, both surfaces with dense appressed purplish brown glands and glabrous, abaxially grayish green, adaxially green, base rounded, apex obtuse and with a mucro. Racemes 5-10 cm, 2-6-flowered; peduncle often with prickles; bracts linear-lanceolate, ca. 3 mm, caducous, with sparse appressed trichomes. Flowers 0.9-1.2 cm. Pedicel 6-8 mm, slender; bracteoles 2, ovate-lanceolate, caducous, glabrous. Calyx campanulate, ca. 4 mm, glabrous; teeth 5, shortly triangular. Corolla yellow; standard subovate, ca. 1 cm, longer than wide, outside with reddish brown dots, with a triangular callus, base tapering into a claw, apex retuse; wings oblong, with long claw, auriculate at one side; keel long obovate, with a dentiform auricle at base. Stamens 0.9-1.2 cm; anthers obovoid, outer side brown. Pistil linear, as long as stamens; style slender; stigma capitate. Legume dark brown, terete, straight to slightly falcate, 15-22 cm × ca. 3 mm, trabeculate, slightly constricted and with a ca. 5 mm separation between seeds, apical beak 1-1.2 cm. Seeds numerous per legume, subterete, ca. 3 × 2 mm; hilum rounded. Fl. and fr. Aug-Dec. 2n = 12, 13, 14.
Stem glabrous, erect, branched from the base, often thick but soft and pithy, reaching 15 ft.
Filament-sheath 9–12(rarely –13) mm., free parts 2–4 mm., anthers 0.5 mm. long.
Ovary glabrous; style glabrous, 2–3 mm. long.
Pod curved, up to 25 cm. long, including a beak of ± 1 cm., 2–3 mm. wide, ± 2 mm. thick in the centre, less at the sutures, 35–40-seeded; septa ± 5 mm. apart (fig. 51/11, 12, p. 346).
Seeds brown, not mottled, elliptical in cross-section, ± 3 × 1.5 × 1.1 mm.
Stipules linear-lanceolate, 6–10 mm. long, erect, pilose, caducous; leaf-rhachis sparsely pilose when young, later glabrous, aculeate on its lower side towards the base, up to 35 cm. long; leaflets in 25–55 pairs, up to 20 mm. long and 3 mm. wide, sparsely pilose when young on margins and midrib beneath, later glabrous.
Raceme glabrous, or with a few hairs when young, 3–12-fiowered; rhachis up to 13 cm. long, including a peduncle, which is nearly always aculeate, up to 4 cm. long; pedicels 6–11 mm. long.
Calyx glabrous except for the margin; receptacle 1 mm., tube 3 mm., teeth triangular, slightly acuminate, 1 mm. long.
Blade of standard brownish-yellow, violet flecked, ± 10 mm. long and wide; appendages wedge-shaped, truncate at the top (fig. 49/12b, p. 332); claw 3 mm.; blade of wing 9 mm. long, toothed but not hooked at the base, 2–3 mm. wide; claw 3 mm.; blade of keel ± 7 mm. long, 2 mm. wide at the base and 4–5 mm. near the apex; basal tooth horizontal, or hooked and pointing downward to the 5 mm. long claw (fig. 49/12a).
Erect, annual or biennial, slightly woody herb, 1–3 m. tall; stems glabrous, or sparsely pilose when young, usually sparsely aculeate.
Calyx 3–4 × 3–4 mm; tube glabrous except for the woolly margins, the teeth 0.5–1 mm long, triangular, ± acuminate.
Raceme (0.8)2.3–15(16.5) cm long, 1–12(14)-flowered; peduncle (0.5)1.5–4(6) cm long, glabrous, nearly always aculeate especially at the base; pedicels (2)4–8(11) mm long, glabrous; bracts 3–5 mm long, linear-lanceolate, caducous; bracteoles 2–3 mm long, filiform, caducous.
Leaves (5.3)9.5–29.5(35) cm long, the rachis aculeate beneath especially towards the base, sparsely pilose when young, later glabrous; petioles 2–15 mm long; leaflets in (11)20–50(55) pairs, 0.75–2(2.6) cm × 1.5–3(5) mm, oblong to oblong-linear, apically emarginate, usually apiculate, sparsely pilose when young on margins and midvein beneath, later glabrous; stipules 5–11 mm long, lanceolate to linear-lanceolate, ± erect, pilose on margins and inner face, at length falling.
Stems glabrous, or very sparsely pilose when young, usually aculeate although often obscurely so.
Seeds pale brown, olive-green or greenish-black, 3 × 1.5 mm, 1.2 mm thick, elliptical in cross-section, the hilum in a small subcentral circular pit surrounded by a white rim aril.
Pod brownish mottled with reddish-brown patches, 12.5–25(28) cm long (including a beak 1–1.5 cm long), 2–3 mm wide, curved, the central area sometimes ridged parallel to the sutures, glabrous, 28–45-seeded; septa 4–6 mm apart.
Standard pale yellowish or cream-coloured, flecked or spotted brownish or purplish, 0.9–1.5 × 0.8–1.4 cm, rounded, apically emarginate, the appendages wedge-shaped and truncate or slightly emarginate apically; wings yellow, 0.9–1.25 cm × 2.5–3 mm, with a short, blunt, unhooked upper basal tooth and with lamellate sculpturing in the upper basal one-half to two-thirds; keel 0.9–1.3 cm × 3.5–5 mm, the blade distinctly longer than wide, the upper edge gently sloping from the apex to the short blunt or slightly acute basal tooth parallel to the claw or slightly downward pointing.