Northern Prairie Wildlife Research Center
Northeast Wetland Flora
Field Office Guide to Plant Species
Bidens laevis (L.) BSP.
- Family: Composite (Compositae)
- Flowering: August-October
- Field Marks: This Bidens is distinguished by its simple leaves and flower heads with
conspicuous yellow rays 3/4-1 1/2 inches long.
- Habitat: Marshes, along streams.
- Habit: Annual or perennial herb from fibrous roots.
- Stems: Upright to spreading, branched, sometimes rooting at the nodes, up to 3 feet long, smooth.
- Leaves: Opposite, simple, narrowly lanceolate to broadly elliptic, pointed at the tip, tapering to the sessile base, toothed, smooth, up to 6 inches long, up to 2 inches wide.
- Flowers: Borne in heads, with yellow rays and a yellow disk, the heads hemispherical, the disk up to 1 inch across, each head subtended by bracts, the outer set of bracts 5-9, narrowly linear.
- Sepals: 0.
- Petals: Some of them forming yellow rays, the rays 7-8 in number, 3/4-1 1/2 inches long, others forming disk flowers up to 1/4 inch long.
- Stamens: 5, purpleblack.
- Pistils: Ovary inferior.
- Fruits: Narrowly wedge-shaped achenes, flat, dark brown to purple, ciliate along the edges, with 2-4 awns, the body of the achene 1/3-1/2 inch long, the awns 1/6-1/4 inch long.
- Notes: The achenes adhere to the furry coats of mammals and are dispersed in this manner. This family is called Asteraceae by Gleason and Cronquist.
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