logo Calflora, a 501c3 non-profit
Taxon  Report  
Erigeron sumatrensis  Retz.
Tropical horseweed
Erigeron sumatrensis is an annual herb that is not native to California.
Siskiyou Del Norte Modoc Humboldt Shasta Lassen Trinity Plumas Tehama Butte Mendocino Glenn Sierra Yuba Lake Nevada Colusa Placer Sutter El Dorado Yolo Alpine Napa Sonoma Sacramento Mono Amador Solano Calaveras Tuolumne San Joaquin Marin Contra Costa Alameda Santa Cruz Mariposa Madera San Francisco San Mateo Merced Fresno Stanislaus Santa Clara Inyo San Benito Tulare Kings Monterey San Bernardino San Luis Obispo Kern Santa Barbara Ventura Los Angeles Riverside Orange San Diego Imperial

Bloom Period
Genus: Erigeron
Family: Asteraceae  
Category: angiosperm  
PLANTS group:Dicot
Jepson eFlora section: eudicot

Name Status:
Accepted by JEF

Alternate Names:
JEFConyza floribunda
JEFConyza sumatrensis
Information about  Erigeron sumatrensis from other sources

[Wikipedia] Origins, Description, Distribution: 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] (link added by Mary Ann Machi)

Suggested Citation
Calflora: Information on California plants for education, research and conservation, with data contributed by public and private institutions and individuals. [web application]. 2024. Berkeley, California: The Calflora Database [a non-profit organization]. Available: https://www.calflora.org/   (Accessed: 07/17/2024).