Conyza bonariensis
Hairy fleabane, asthmaweed, wavy-leaf fleabane, flax-leaf fleabane, argentine fleabane, South American horseweed
Description: annual or biennial
Place of origin: South America
Urban habitat: commonly found in disturbed sites, along roadsides.
Ecological function: disturbance-adapted colonizer.
History: Found from Oregon to Virginia across the southern US and in Hawaii, Conyza bonariensis is widespread throughout the world in tropical and warm-temperate regions and is commonly considered to be a weed. The plant has been found to have allelopathic properties, which inhibit the growth of nearby plants. The plant is used for grazing in Sudan and for medicinal purposes in Lesotho for treatment of sore-throat and ringworm.