Northeast Wetland Flora
Field Office Guide to Plant Species
Bidens discoidea (Torr. & Gray) Britton
- Family: Composite (Compositae)
- Flowering: August-October
- Field Marks: The characters which distinguish this species are the pinnately compound leaves, the rayless flower heads, and the 2-5 long, spatulate outer bracts that subtend each head.
- Habitat: Swamps, often on fallen logs or growing on the base of trees in standing water.
- Habit: Annual herb with fibrous roots.
- Stems: Upright, branched or unbranched, very slender, smooth, often red, up to 5 feet tall.
- Leaves: Opposite, variable, the lowest pinnately compound with 3 leaflets, the upper often simple, lanceolate, tapering to a long point at the tip, tapering to the base, smooth, membranaceous; leaf stalks up to 1 inch long, smooth.
- Flowers: Many flowers in heads, with several heads on slender stalks up to 2 inches long, each head rayless, the disk 1/4-1/3 inch across, each head subtended by 2-5 smooth, outer bracts.
- Sepals: 0.
- Petals: 5, united to form tubular disk flowers.
- Stamens: 5.
- Pistils: Ovary inferior.
- Fruits: Achenes obovate to oblanceolate, tapering to the base, hairy, 1/4-1/3 inch long, with a pair of hairy awns about 1/8 inch long.
- Notes: Gleason and Cronquist call this family Asteraceae.
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