Bidens is a genus of flowering plants in the family Asteraceae. It contains about 200 species. The common names beggarticks, black jack, burr marigolds, cobbler's pegs, Spanish needles, stickseeds, tickseeds and tickseed sunflowers refer to the achene burrs on the seeds of this genus, most of which are barbed. The generic name refers to the same fact; it means "two-tooth", from Latin bis "two" + dens "tooth".