Ageratina adenophora

Perennial herb or subshrub to 2.5 m high; stems usually purplish when young, glandular-pubescent. Leaves opposite, triangular to rhombic, to 12 cm long, 6 cm wide, sparsely puberulent; margin serrate; petiole 10–25 mm long; base cuneate to obtuse or nearly truncate; apex acute to acuminate. Inflorescence of numerous capitula; capitula 5–8 mm diam.; involucre campanulate, 3.5–4 mm long; bracts linear or linear-lanceolate, green to reddish, glandular-pubescent. Florets 40–50, white to purplish, c. 3.5 mm long. Cypselas cylindric, 1–2 mm long, black-brown, glabrous; pappus of bristles, 3–4 mm long, white. Flowers Sep.–Apr.