South Dakota Native Plant Research
Asteraceae : Conyza canadensis

Asteraceae : Conyza canadensis


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Family Name


Common Name

Canadian horseweed

Native American Name

Lakota: čhaŋȟlóǧaŋ waštémna iyéčheča


Conyza canadensis is an annual, herbaceous plant growing from 0.3 10 to 1.5 m tall, mostly simple or branching above if injured, with sparsely hairy stems. The simple, alternate leaves are sessile, narrowly oblanceolate to linear 2–10 cm long and generally <1 cm wide, with entire to coarsely toothed margins. The leaves grow in a spiral up the stem and the lower ones often wither early. The inflorescence is a terminal cluster of flower heads 1 cm in diameter, with an involucre, of overlapping bracts, that is 3-4 mm long and green. Twenty to 30 ray flowers with white to pale purple ligules and a few yellow disc florets in the center. The fruit are hairy achenes with an abundant pappus. Horseweed is a weed in open cultivated and disturbed ground flowering from June through September throughout South Dakota.

Additional Notes

Canadian horseweed may become weedy or invasive in some areas or habitats.

Horticulture Notes

This plant is not recommended for horticultural uses.

Asteraceae : Conyza canadensis