Slender, more or less erect annual to c. 1 m high, stems glabrous, often gland-dotted. Ochreas ciliate at apex, glabrous or with scattered hairs on sheath. Leaves lanceolate, 5–15 cm long, 8–30 mm wide, margins and main veins with short antrorsely appressed bristles, lamina glabrous, minutely gland-dotted on at least lower surface; petiole 3–10 mm long. Inflorescence slender, cylindric, often interrupted and drooping, 4–18 cm long, 3–5 mm diam.; peduncle 3–20 mm long; perianth segments 2–3.5 mm long, pale green to white, rarely tinged pink, prominently gland-dotted, free for about two-thirds their length. Nut broadly ovate, biconvex or plano-convex, c. 3 mm long, 2 mm wide, dull and slightly roughened, dark brown. Flowers Jan.–May.
VVP, VRiv, MuF, GipP, OtP, WaP, Gold, CVU, NIS, EGL, EGU, HSF, HNF, OtR, Strz, MonT, VAlp. Also WA, Qld, NSW, ACT (naturalised), Tas. New Zealand, most of Europe. A common riparian herb in the eastern half of the State, rather rare in the west (e.g. Otway Range, Winchelsea, Kerang area), sometimes weedy, and possibly introduced. It is variously treated as native or naturalised in the other States in which it occurs.
