Erigeron sumatrensis (syn. Conyza sumatrensis) is an annual herb probably native to South America, but widely naturalised in tropical and subtropical regions, and regarded as an invasive weed in many places.Pruski, J.F. & G. Sancho. 2006. Conyza sumatrensis var. leiotheca (Compositae: Astereae), a new combination for a common neotropical weed. Novon 16(1): 96–101It is a perennial in the Western Cape of South Africa.
In the British Isles it is known as Guernsey fleabane. Other common names include fleabane, tall fleabane, broad-leaved fleabane, white horseweed, and Sumatran fleabane.
Description When fully grown (in summer or autumn), Erigeron sumatrensis reaches in height. Flowers are white rather than purple-pink. Its leaves are like dandelion leaves, but longer, thinner and more like primrose leaves in colour and texture. Its seeding heads are like dandelions, but straw coloured and smaller.See pictures at International Environmental Weed Foundation In certain countries the plant has started to exhibit resistance to herbicides.Sumatran Fleabane, Weedscience.org
Distribution It probably originates from South America, but is now naturalised in North America, Europe, Africa, Flora of Zimbabwe: Conyza sumatrensis Asia,Sumatran Fleabane in Japan and Australasia.Pacific Island Ecosystems at Risk (PIER): Conyza sumatrensis It poses a significant threat to wildlife conservation areas and other reserves. In Britain, of the non-native former Conyza species, it is the second most abundant (after Erigeron canadensis) and is typically found in London and the South East of England. It was first recorded in London by Brian Wurzell in 1984, and noted in France at Saint-Sozy (Dordogne) in 2006.
Taxonomic note Older literature such as Flora of Turkey may quote Conyza albida Willd. ex Spreng. intending what is now E. sumatrensis Retz., and should be taken as such; likewise other literature references may do so; the type has subsequently been revised and Conyza albida Willd. ex Spreng. is now viewed as a synonym for Erigeron floribundus (Kunth) Sch.Bip. Erigeron Floribundus and E. Sumatrensis (Asteraceae) In The USA And Mexico, 2018 by Guy L. Nesom, p16 in section on Erigeron floribundus
Photographic description
References
External links
Erigeron sumatrensis occurrence data from GBIF