water-marigold, beggarticks, stickseeds, tickseeds, tickseed sunflowers, devil's sticktight, bur-marigolds
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
can be weedy
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.
moist habitats, wetlands, still or slow-moving shallow water; lakes, ponds, rivers, and streams
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.