Scientific name
Bidens L.
Common names
water-marigold, beggarticks, stickseeds, tickseeds, tickseed sunflowers, devil's sticktight, bur-marigolds
Family
Asteraceae
Similar genera
Aciotis, Acmella, Boltonia, Eclipta, Gymnocoronis, Hypericum, Hyptis, Sphagneticola
Native distribution
cosmopolitan; mainly subtropical, tropical, and warm-temperate New World
Species cultivated
Bidens beckii Torr. ex Spreng. [syn: Megalodonta beckii (Torr. ex Spreng.) Greene.] is rarely cultivated, but may be found in specialty stores or for trade with hobbyists
these amphibious to wetland species are offered as garden ornamentals
Bidens aristosa (Michx.) Britton
B. cernua L.
B. connata Muhl. ex Willd.
B. coronata (L.) Britton [synonym of Bidens trichosperma (Michx.) Britton]
B. frondosa L.
B. laevis (L.) "Britton, Sterns & Poggenb."
B. polylepis S.F.Blake
Adventive distribution
Weed status
can be weedy
Habit
amphibious to emergent, sometimes floating, helophytic herbs
Brief description
Annual or perennial. Stem ascending to erect, often striate. Leaves opposite decussate, sessile or petiolate; leaf blade simple, lobed, or compound; margins entire to serrate when emersed (submerged leaves appearing whorled and finely dissected in B. beckii). Inflorescence a terminal head, solitary or in cymes, pedunculate, heads usually radiate; involucre hemispheric; phyllaries biseriate. Ray florets absent or few, usually sterile, ligulate, yellow or white; disk florets bisexual, fertile, tube 5-lobed, yellow to orange.
Natural habitat
moist habitats, wetlands, still or slow-moving shallow water; lakes, ponds, rivers, and streams
Additional comments
Bidens contains approximately 250 species, most of which are in wetland habitats and tolerate periods of submersion. Bidens beckii (=Megalodonta beckii) is the only truly aquatic species.
