Annual herb to 65 cm high; stems slightly woody towards base, narrowly winged when young, sometimes scabrid. Leaves linear-oblong to oblanceolate, 15–80 x 3–14 mm, prominently auriculate-cordate at the base, subacute at the tip, glabrous or almost so. Cymes (2–)3–15-flowered; peduncle 1.5–10 mm long. Hypanthium suburceolate, 2–2.5 mm long including triangular sepals, often minutely puberulent/papillate, sinus-horns prominent in bud. Petals obovate, pink. Stamens 4–8. Style (0.5–)1.5–3 mm long. Capsule globose, 1.8–2.5(–3.5) mm in diam., not or only slightly exserted from hypanthium, very fragile, translucent reddish-brown. Seeds c. 0.4 mm long, yellowish brown.