Bidens trichosperma (Michx.) Britton
Family: Asteraceae
northern tickseed-sunflower, tall swamp marigold
Bidens trichosperma image
Merel R. Black  
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/biennial, 6"-60" tall, smooth forb
Leaves: pinnately-divided into 3-7 lance-like, pointed segments
Flowers: head 1 1/2"-2 1/2" wide with 8 yellow rays 1/2"-1" long, leafy bracts usually shorter than the 1/3"-1/2" wide disk; inflorescence of a few long-stalked heads; blooms Aug.-Oct.
Fruits: dry, dark, with 2- bristly awns, mostly flat, 2 1/2 to 4 times as long as wide fruit drawing
Habitat: wet; meadows, marshes, shores
Conservation Status: Native