Conyza canadensis (L.) Cronquist
Canadian horseweed, Horseweed
Asteraceae (Aster Family)
USDA Symbol: COCA5
A coarse weed with erect bristly-haired stem that has branching clusters of small, cup-like, greenish-white flower heads arising from upper leaf axils. The minute white rays do not spread and thus are not showy; the numerous disk flowers are yellow.
An annual that thrives on bare soil, Horseweed is soon crowded out as perennials become established. Originally a North American plant, it has spread to Europe, where it colonizes open disturbed sites. Indians and early settlers used a preparation of its leaves to treat dysentery and sore throat.
From the Image Gallery
Bloom InformationBloom Color: White
Bloom Time: Jul , Aug , Sep , Oct , Nov
DistributionUSA: AK , AL , AR , AZ , CA , CO , CT , DC , DE , FL , GA , HI , IA , ID , IL , IN , KS , KY , LA , MA , MD , ME , MI , MN , MO , MS , MT , NC , ND , NE , NH , NJ , NM , NV , NY , OH , OK , OR , PA , RI , SC , SD , TN , TX , UT , VA , VT , WA , WI , WV , WY
Canada: AB , BC , MB , NB , NL , NS , NT , ON , PE , QC , SK
Native Distribution: Throughout North America, except parts of far north.
Native Habitat: Fields, roadsides, and waste places.
Growing ConditionsWater Use: Medium
Light Requirement: Sun
CaCO3 Tolerance: Low
BenefitConspicuous Flowers: yes
From the National Organizations DirectoryAccording to the species list provided by Affiliate Organizations, this plant is on display at the following locations:
Pineywoods Native Plant Center - Nacogdoches, TX
Sibley Nature Center - Midland, TX
Brackenridge Field Laboratory - Austin, TX
Stengl Biological Research Station - Smithville, TX
Wildflower Center Seed BankLBJWC-0148 Collected 2007-09-04 in Travis County by Lady Bird Johnson Wildflower Center
Recommended Species Lists
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Additional resourcesUSDA: Find Conyza canadensis in USDA Plants
FNA: Find Conyza canadensis in the Flora of North America (if available)
Google: Search Google for Conyza canadensis
MetadataRecord Modified: 2009-09-26
Research By: TWC Staff