Horseweed
Conyza canadensis (L.) CronquistAsteraceae

common name synonyms: Marestail, Canadian Horseweed, Bitterweed, Canadian Fleabane

scientific name synonyms: Erigeron canadensis, E. pusillus

subclass: Dicotyledoneae

superorder: Asteridae

order: Asterales

growth form: herb

life history: annual, biennial

level of invasiveness: invasive

weedy in native range: Yes

noxious weed in the u.s.: No

type of introduction: Unknown

number of vectors: 1.0

introduced range: Czech Republic, Europe, Poland, France, Britain, Denmark, Portugal

native range: North America

notes: Conyza=Erigeron??; found in cult. Grounds and waste places; weedy (Maillet 1997), widely naturalized; considered invasive in U.S. (PUSDA); Kornas (1990) says in Poland for 100+ yrs.; weed of cultivation, present in 1930 in Cyprus, 1892 in Tunisia, Paris 1698, Blois (France) 1655(Guillerm); abundantly established on cultivated and waste ground, dunes and walls, esp. in the southeast, first recorded in the London area in 1690, but still almost unknown in Ireland, a hybrid with native Erigeron acer (X Conyzigeron huelsenii; E. X huelsenii) has been recorded; known for 80 years in Denmark as a rarity, spread after 1930 to become general, brought from America to Europe about 275 yrs. before 1961, in the skin of a bird which had been stuffed with its plumed fruits, already weedy in Britain by 1877, often found at bombed sites in England; weed in Honduras, Surinam, Chile, Colombia, Mexico, etc.; making recent trek along railways from Sweden to Norway

invasiveness notes: invasive




Credits: Credits: (c) 2001-2006 J. Forman Orth