Biology:Erigeron sumatrensis

Erigeron sumatrensis
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Asterales
Family:	Asteraceae
Genus:	Erigeron
Species:	E. sumatrensis
Binomial name
	Erigeron sumatrensis; Retz.
Synonyms
	List Dimorphanthes floribunda E.H.L.Krause ; Makino Baccharis ivifolia ; Blanco Conyza albida ; Willd. ex Spreng. Conyza altissima ; Naudin ex Debeaux DC. ; (Cabrera) Cabrera Cuatrec. ; DC. V.M.Badillo ; E.Walker Cass. ; Sch.Bip. (Bonnet) Humbert ; Erigeron bonariensis var. microcephalus Eschenbachia ambigua ; Conyza floribunda var. subleiotheca Conyza naudinii ; Dimorphanthes ambigua Erigeron albidus ; Cabrera Moris ; Conyza ambigua Conyza bonariensis var. microcephala ; Conyza bonariensis f. subleiotheca Conyza erigeroides ; (Cuatrec.) J.B.Marshall Bonnet ; C.Presl (Willd. ex Spreng.) A.Gray ; (Bonnet) Bonnier Erigeron musashensis ; Erigeron naudinii Erigeron crispus subsp. naudinii ; Aster ambiguus Conyza groegeri ; Conyza sumatrensis (Retz.) Erigeron ambiguus ; ;

Short description: Species of flowering plant in the daisy family Asteraceae

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.^[1]^[2]^[3]

In the British Isles it is known as Guernsey fleabane.^[4] Other common names include fleabane, tall fleabane, broad-leaved fleabane, white horseweed, and Sumatran fleabane.^{[citation needed]}

Description

When fully grown (in summer or autumn), Erigeron sumatrensis reaches one to two metres 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.^[5] In certain countries the plant has started to exhibit resistance to herbicides.^[6]

Distribution

It probably originates from South America, but is now naturalised in North America, Europe,^[7] Africa,^[8] Asia,^[9] and Australasia.^[10] 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,^[11] and noted in France at Saint-Sozy (Dordogne) in 2006.^[12]

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. ^[13]

Photographic description

Tall and tending to end up leaning over
Side phyllaries hairy and green, without red tips, and lacks prominent white petals, which may have a purple tinge
Head from above, ray petals with purple tinge
Individual flower from within head, 5-petalled
Individual flower from within head, 5-petalled
Base leaves quite broad, lobey and hairy, but green-looking not conspicuously grey
Colony of rosettes
Emerging plant, green-looking
Flowering whilst still small
Stem leaf
Stem leaf base
Stem leaf near tip
Stem leaf underside
Stem leaf underside
Stem
Inflorescence prior to heads expanding with pappus
Seeding