A genus of flowering plants in the aster family, Asteraceae. 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, with two sharp pappi at the end. The generic name refers to the same character; Bidens comes from the Latin bis (“two”) and dens (“tooth”).
The plants are zoochorous; their seeds will stick to clothing, fur or feathers, and be carried to new habitat. This has enabled them to colonize a wide range, including many oceanic islands.