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Bidens cernua

Asteraceae: Bidens frondosa L.
(common beggartick, devil's beggartick )

There are 7 species of the genus Bidens, the beggarticks, in Nova Scotia. All (in N.S.) are annual herbs growing in wet places. Two- or 4-awned fruits stick to animals or clothing, hence the inclusion of "bur" or "tick" in common names. Bidens frondosa "Bidens" comes from the Latin for two teeth, referring to the awns. The flowers of Bidens spp. may be discoid or radiate, with yellow rays in the radiate types. Leaves are always opposite. B. frondosa has petiolate, pinnately compound toothed leaves with 3-5 leaflets, 5-8 floral bracts, usually lacks floral rays and has 2-awned fruit. Plants vary in height between 20 cm and 1.5 meters accordig to site conditions.

B. frondosa occurs at edges of ponds and streams and in moist, disturbed soils around human habitations, e.g., in ditches. The species is broadly distributed in North America, absent only from Yukon, NWT, Nunavut and Labrador. 1 It is a weedy species which is native to North America and introduced and expanding in Europe.2 (This is a notable exception to the more usual pattern in which weedy European species have followed colonists to North America.)
Sources | Notes & Refs | Selected Web Resources | Line Drawing

Click on images for larger versions.

Sep. 6, 2008. Haliax County: Point Pleasant Park (Halifax). Photographer: JackPine.
Bidens frondosa Bidens frondosa
Bidens frondosa stem
Bidens frondosa

Leaves have sparse, soft hairs, more so on the underside.

Bidens frondosa
Bidens frondosa

Older flower with developing fruit.

Bidens frondosa, fruit

 Bar is 1 cm.

Oct. 22, 2008. Haliax County: Frog Pond (Halifax). Photographer: JackPine.
Bidens frondosa, Habit Bidens frondosa, Inflorescense & Seeds

 Bar is 1 cm.

Selected Web Resources

Notes & References

  1. NatureServe Explorer [Accessed 7 Sep. 2008]
  2. Cofikunceleb, K., Terzioglu, S. & Vladimirov, V. (2007). A new alien species for the flora of Turkey: Bidens frondosa L. (Asteraceae). Turkish Journal of Botany, 31: 477-479. PDF at [Accessed 7 Sep. 2008]