Northern Prairie Wildlife Research Center
Northeast Wetland Flora
Field Office Guide to Plant Species
Bidens comosa (Gray) Wiegand
- Family: Composite (Compositae)
- Flowering: August-October
- Field Marks: This species is distinguished by its simple leaves and its rayless heads
subtended by 6-10 leaf-like outer bracts.
- Habitat: Wet ground.
- Habit: Annual herb with fibrous roots.
- Stems: Upright, branched, slender or stout, smooth, up to 6 feet tall.
- Leaves: Opposite, simple, elliptic to lanceolate, pointed at the tip, tapering to a winged stalk, coarsely toothed or sometimes with a pair of lobes at the base, up to 8 inches long, smooth.
- Flowers: Many crowded in heads, with few to several heads on stout, smooth stalks up to 4 inches long, each head usually without rays but with about 30 tubular disk flowers, each head subtended by 6-10 leafy outer bracts; disk flowers pale yellow, up to 1/4 inch long.
- Sepals: 0.
- Petals: 4, united to form tubular disk flowers.
- Stamens: 5.
- Pistils: Ovary inferior, sparsely hairy.
- Fruits: Achenes crowded into heads, each achene flat, smooth except for the ciliate edges, oblanceolate, 1/3-1/2 inch long, with 2-5 stout, barbed awns at the tip.
- Notes: Gleason and Cronquist call this family Asteraceae. This and the other species of Bidens with barbed awns allow the fruits to stick in the fur of animals as a means of seed dispersal.
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