Ageratina adenophora (Spreng.) R.M.King & H.Rob.
Mexican devil
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.
N.: common in N. Auckland, local in S. Auckland especially Coromandel.
Mexico 1931
Usually forest margins and clearings, waste places, scrubland, streamsides, rarely in swamps.
FL Aug-Dec-(Mar).
Poisonous (Connor 1977).
A trypetid stem gall fly was introduced to N.Z. in 1958 in an attempt to control this aggressive weed [Hoy, J. M., New Zealand J. Sci. 3 : 200-208 (1960)]. Mexican devil has usually been known in N.Z. as Eupatorium adenophorum and also as E. glandulosum.
