Annual herb, 1–3 m tall. Stems erect, simple or few-branched, sparsely pilose, mainly on the young parts, or glabrous. Leaves alternate, shortly petiolate (petiole 0.5–1 mm), linear and grass-like to very narrowly elliptic, 3–25≈0.3–1.8(–2) cm, acute, base cuneate, slightly rough with short hairs, mainly on the upper surface, to glabrescent. Flowers purple to whitish, in many-flowered simple or few-branched terminal racemes up to 60 cm long, rachis pilose; bracts ovate-lanceolate, 4–10≈0.5–1.5 mm, caudate with a thread-like apex, persistent; bracteoles ovate-lanceolate, 2.5–3≈0.5–1 mm, persistent; pedicels 5–14 mm, pilose. Posterior sepal keel-shaped, 4.5–6.5≈3–4 mm, pilose; wing sepals obliquely suborbicular, (9–)10–13.5 mm in diameter, glabrous or minutely ciliate; anterior sepals keel-shaped, 4–6≈3–4 mm, pilose, free. Upper petals obliquely elliptic, 5–7≈3–4 mm; carina 8.5–11 mm long; crest 3–4 mm long, fimbriate. Stamens 8. Capsule oblong-obovate in outline, 8–11≈5.5–7.5 mm, winged, wing 0.5–0.8 mm wide, ciliate. Seeds cylindric, 3.2–4(–6)≈1.8–2 mm, with white silky hairs ± 2 mm long, exceeding the base of the seed; caruncle subsymmetric, kidney-shaped, with three very short appendages.