Northern Prairie Wildlife Research Center
Southern Wetland Flora
Field Office Guide to Plant Species
Conyza canadensis (L.) Cronq.
- Family: Aster (Asteraceae)
- Flowering: June-November
- Field Marks: This species is distinguished by its very crowded, narrow, hairy, alternate
leaves and its many tiny heads of flowers.
- Habitat: Moist or dry soils in old fields, prairies, glades, along roads, disturbed open areas.
- Habit: Usually biennial herb with thickened roots.
- Stems: Upright, branched above, usually densely hairy, up to 10 feet tall.
- Leaves: Alternate, simple, crowded, spatulate to linear, pointed at the tip, tapering to the base,
sparsely toothed, hairy, up to 4 inches long.
- Flowers: Flowers many, crowded together into heads; each head up to 1/6 inch across,
subtended by several very narrow green bracts; some flowers with tiny white rays, or rays absent;
other flowers tubular.
- Sepals: 0.
- Petals: 4-parted, united,
- Stamens: 5.
- Pistils: Ovary inferior.
- Fruits: Achenes elongated, with a tuft of hairs at the tip.
- Notes: This coarse weed used to be placed in the genus Erigeron. The pollen may cause hay
fever in some individuals. This species is usually not grazed by domestic livestock because of its
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