Flora of New Zealand Series

ageratum

Erect or ascending annual herb, up to c. 1 m tall. Stems densely clothed in long eglandular and short glandular hairs above, becoming almost glabrous and sometimes somewhat woody toward base. Petiole hairy and glandular, 5-20-(50) mm long; lamina hairy and glandular especially on lower surface, ovate to ovate-triangular, acute, truncate to cordate, crenate-serrate, (12)-25-60-(100) × (12)-15-50-(70) mm; uppermost lvs smaller, sometimes with few teeth. Capitula c. 3-7 mm diam., in dense clusters; peduncles hairy and glandular. Involucral bracts ± equal, sometimes with supplementary bracts outside, oblong-triangular to lanceolate, acuminate, hairy and glandular, 4-5-(6) mm long. Florets usually blue and with conspicuous blue stigmas, rarely corolla and stigmas white. Achenes black, sparsely hairy, 1.4-1.8 mm long, with 5-(6), aristate, fimbriate scales.

K.: common on Raoul and nearby islets.

Mexico, C. America, W. Indies 1888

Waste places and disturbed areas.

FL Jan-Dec.

Ageratum is cultivated in N.Z. but has become wild only in the Kermadec Is. Early records of A. conyzoides are misidentifications of A. houstonianum.