Ageratina adenophora (Spreng.) R.M.King & H.Rob.

Erect perennial herb to subshrub, 1–3 m tall. Stems densely clothed in stalked glandular hairs at least above, sometimes also with eglandular hairs, sometimes tinged purple, much-branched. Lvs opposite; petiole glandular, 15–35–(50) mm long; lamina glabrescent to minutely glandular especially on veins of lower surface, ovate-rhombate to deltate, acute to acuminate, coarsely crenate-serrate except near base, 55–80–(120) × 35–70–(90) mm; uppermost lvs smaller, often ± elliptic and entire. Capitula 5–7 mm diam., numerous in terminal corymbs; peduncles densely glandular. Involucral bracts in 2 ± equal rows, with shorter, narrower supplementary bracts outside, narrow-elliptic to lanceolate, glandular, 4.5–5.5 mm long. Florets white. Achenes black, 5-angled, glabrous, 1.3–1.8 mm long.

[From: Webb et al. (1988) Flora of New Zealand. Volume 4.]

Flowering: Aug.–Dec.–(Mar.)