Bidens cernua L.

• Authority

  Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

• Family

  Asteraceae

• Scientific Name

  Bidens cernua L.

• Description

  Species Description - Annual 1–10(–40) dm, glabrous or the stem scabrous-hispid; lvs sessile, often basally connate, simple, lance-linear to lance-ovate, coarsely serrate to subentire, 4–20 x 0.5–4.5 cm; heads hemispheric, many-fld, the disk 12–25 mm wide, commonly nodding at least in age; outer invol bracts 5–10, lance-linear, unequal, usually rather leafy and spreading, commonly surpassing the disk; rays (6–)8, yellow, to 1.5 cm, or none; receptacular bracts thin and soft, mostly yellowish at the blunt tip; disk- corollas mostly 5-lobed; anthers shortly exserted; achenes 5–8 mm, the margins tending to be thickened, cartilaginous, and pale at maturity, as also the finally convex (broadly dome-shaped) summit; pappus of (2–)4 retrorsely barbed awns; 2n=24. Low, wet places; widespread in temp. parts of the N. Hemisphere, and throughout our range. Aug.–Oct. (B. elliptica; B. filamentosa; B. glaucescens; B. gracilenta; B. leptopoda; B. prionophylla)

• Common Names

  bur marigold