Eupatorium cannabinum
Common name
Hemp agrimony
Family
Asteraceae
Flora category
Vascular – Exotic
Structural class
Dicotyledonous Herbs - Composites
Conservation status
Not assessed
Brief description
Tall upright herb with downy hairy branches up to 2 m tall, leaves in pairs, stalked and divided into 3 segments, each with toothed edges, flowerheads a flat mass of small pink flowers on top of each stem.
Distribution
Locally well established in South Taranaki and Wanganui District.
Habitat
Wetlands and riparian margins of water bodies, particularly areas that are rich in Nitrogen.
Features
Perennial herb with a woody rootstock, shoots erect 0.3-2 m, simple or short branched, downy striate. Basal leaves oblanceolate, petiolate; cauline leaves subsessile, 3 (-5)-pinnate with elliptic-acuminate toothed pinnae 5-10 cm, short glandular-hairy. Inflorescence a dense terminal corymb, each head with 5-6 reddish-mauve to white florets, 1-2 mm diameter and c. 10 oblong purple-tipped involucral bracts c. 6 mm. Achenes blackish, 5-angled, gland dotted, pappus whitish.
Similar taxa
Not similar to other wetland plants with possible exception of Bidens spp. that lack hairs and have coarser toothed leaflets.
Flowering
January - March
Flower colours
Red/Pink, Violet/Purple, White
Fruiting
Autumn
Life cycle
Perennial. Produces thousands of tiny wind dispersed seeds. Also has the potential to spread by water and contaminated machinery, deliberate planting.
Year naturalised
1975
Origin
Eurasia, North West Africa
Reason for introduction
Ornamental plant
Control techniques
Not controlled in New Zealand.
Etymology
eupatorium: Commemorating Mithridates Eupator, king of Pontus and Armenia Minor in northern Anatolia (now Turkey) from about 120–63 BC, who is said to have discovered one of the species as an antidote for poison.
cannabinum: Like Cannabis, hemp
Attribution
Factsheet prepared by Paul Champion and Deborah Hofstra (NIWA).
References and further reading
Clapham, A.R.; Tutin, T.G.; Warburg, E.F. (1962). Flora of the British Isles. Cambridge University Press, Second Edition. 1269pp.
Webb, C.J.; Sykes, W.R.; Garnock-Jones, P.J. (1988). Flora of New Zealand Volume 4: Naturalised pteridophytes, gymnosperms, dicotyledons. Botany Division, DSIR, Christchurch.