Bidens tripartita

Erect annual herb to 1 m high; stems glabrous or sparsely hairy. Leaves broad-lanceolate to broad-ovate in outline, mostly 6–15 cm long, 2–7 cm wide, usually 3-lobed, sometimes simple or 5-lobed, c. glabrous except for tiny antrorse hairs on margins and veins, margins toothed or shallowly lobed; petiole winged, to c. 4 cm long. Capitula 10–25 mm diam.; outer involucral bracts leaf-like, c. spathulate, to c. 40 mm long, often far exceeding florets; inner bracts lanceolate, 8–12 mm long. Ray florets yellow. Cypselas oblong-cuneate, 4–8 mm long, compressed, ribbed, retrorsely barbed on ribs; pappus of 2–4 awns, 1.5–4 mm long. Flowers autumn and winter.