Ageratum L.

2 species naturalized Aust.; Qld, NSW, NT

*Ageratum houstonianum Mill.

Annual, decumbent to erect herb, with many stems up to 50 cm long. Leaves opposite, ovate to triangular; the blades 2–3 cm long, 2–3 cm wide, crenate-serrate; petioles 10–15 mm long. Heads terminal in clusters. Involucre 3–5 mm diam.; the bracts green, in 2–3 rows. Florets all tubular, mauve. Cypselas angled, dark brown to black, c. 2 mm long. Pappus of subulate scales c. 2 mm long. Coast. Waste places. Introd. from Central America. Fl. most of the year