Bidens cernua L.
Family: Asteraceae
nodding beggar-ticks, nodding bur-marigold
Bidens cernua image
Scott A. Milburn  
Etymology: Bidens: derived from Latin bis, "twice," and dens, "tooth," hence meaning "2-toothed" and referring to the bristles on the achenes
Plants: erect, annual, 4"-40" tall forb
Leaves: mostly stalkless, undivided but with coarse teeth
Flowers: head 1 1/4"-2" wide with yellow rays to 1/2" long, center disk to 1/2"-1" wide, leafy bracts usually longer than the disk; inflorescence of many hemispherical heads (often nodding with age) in large, loose, stalked clusters; blooms Aug.-Oct.
Fruits: dry, with 2-4 barbed awns fruit drawing
Habitat: wet; meadows, marshes, shores
Conservation Status: Native