Bidens bipinnata is an annual herb, 30-170 cm tall, stem square.
Leaves opposite, stalk 2-5 cm, blade about 2-15 cm long, 2-3 times pinnately divided, ultimate segments usually rounded.
Flowers yellow, to 0.6 cm wide, longer than wide, rays few, usually shorter than disk, outer bracts at base of flower head 7-10, shorter than the inner, membranous bracts, flower stalks stiff, elongate.
Fruit dry, 1-seeded (achenes) linear 4-sided to 1-1.3 cm topped by 3-4 stout, pale tooth-like barbed bristles (awns) that attach to fur or clothing for dispersal, Aug.-Oct.
Wetland status: UPL.
Frequency in NYC: Infrequent but apparently widespread.
Habitat: Open, disturbed areas, edges.