Northeast Wetland Flora
Field Office Guide to Plant Species
Bidens polylepis Blake
- Family: Composite (Compositae)
- Flowering: August-October
- Field Marks: The distinguishing features of this species are its pinnately compound leaves, conspicuous ray flowers, 10 or more bracts subtending each flowering head, and its usually awnless achenes.
- Habitat: Wet ground, roadside ditches.
- Habit: Annual or biennial herb with fibrous roots.
- Stems: Upright, much branched, usually hairy, up to 3 feet tall.
- Leaves: Opposite, pinnately compound, the leaflets linear to lanceolate, coarsely toothed or shallowly lobed, smooth, up to 3 inches long.
- Flowers: Many crowded in heads, with numerous heads on slender, rough stalks up to 4 inches long, each head with about 8 bright yellow rays up to 1 inch long and numerous tubular disk flowers, each head subtended by 10 or more leafy bracts.
- Sepals: 0.
- Petals: Some united to form flat rays, others united to form tubular disk flowers.
- Stamens: 5.
- Pistils: Ovary inferior, sparsely hairy.
- Fruits: Achenes crowded into heads, each achene flat, sparsely hairy on the faces, with stiff hairs on the edges, up to 1/4 inch long, usually with a pair of 2 short awns at the tip, or the awns absent.
- Notes: This family is Asteraceae according to Gleason and Cronquist. This species is expanding its range from the midwest eastward.
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