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 Latinbis ("two") and dens ("tooth").
Bidens includes roughly 230 species which are distributed worldwide throughout many tropical and warm temperate regions. Species occur in the Americas, Africa, Polynesia, Europe and Asia.
Phylogeny, taxonomy and diversity
Despite their global distribution, the systematics and taxonomy of the genus has been described as complicated and unorganized. The genus include roughly 230 species.
Bidens is closely related to the American genus Coreopsis, and the genera are sometimes difficult to tell apart; in addition, neither is monophyletic.
Bidens 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. Some of these species occur only in a very restricted range and several are now threatened with extinction, notably in the Hawaiian Islands. Due to the absence of native mammals on these islands, some of the oceanic island taxa have reduced burrs, evolving features that seem to aid in dispersal by the wind instead.
^ abcdKnope, M. L., Funk, V. A., Johnson, M. A., Wagner, W. L., Datlof, E. M., Johnson, G., ... & Carlquist, S. (2020). Dispersal and adaptive radiation of Bidens (Compositae) across the remote archipelagoes of Polynesia. Journal of Systematics and Evolution, 58(6), 805-822.
^ abGanders, F. R., Berbee, M., & Perseyedi, M. (2000). ITS base sequence phylogeny in Bidens (Asteraceae): Evidence for the continental relatives of Hawaiian and Marquesan Bidens. Systematic Botany,25(1), 122-133.
^ abBidens. New South Wales Flora Online. National Herbarium, Royal Botanic Garden, Sydney.