Bidens is a genus of flowering plants in the aster family, Asteraceae. The genus include roughly 230 species which are distributed worldwide. Despite their global distribution, the systematics and taxonomy of the genus has been described as complicated and unorganized. The common names beggarticks, black jack, burr marigolds, cobbler's pegs, Spanish needles, stickseeds, tickseeds and tickseed sunflowers refer to the fruits of the plants, most of which are bristly and barbed. The generic name refers to the same character; Bidens comes from the Latin bis ("two") and dens ("tooth").

The family Asteraceae, with the original name Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae were first described in the year 1740. The number of species in Asteraceae is rivaled only by the Orchidaceae, and which is the larger family is unclear as the quantity of extant species in each family is unknown.