Bidens

Bidens is a genus of flowering plants in the family Asteraceae, commonly known as beggar-ticks, beggarticks, or tickseeds. The genus includes roughly 200 described species of annuals and perennials, with a distribution centered in the Americas but occurring in Africa and Asia as well. They are herbaceous plants that may be erect, sprawling, or climbing, often with opposite leaves that can be simple, pinnate, or lobed. Inflorescences are flower heads typical of the Asteraceae, usually with yellow central disc florets and small ray florets that can be white, yellow, or absent depending on the species. A hallmark of Bidens is the seed habit: barbed achenes that cling to fur or clothing, which has given rise to the common name beggar-ticks.

Habitat and ecology: Bidens species occur in wetlands, meadows, roadsides, and other disturbed habitats across temperate to tropical regions. They are typically insect-pollinated, and many produce seeds that are adapted for attachment to animals or objects, aiding dispersal.

Taxonomy and diversity: The genus belongs to the tribe Heliantheae within Asteraceae. Notable species include Bidens pilosa (Spanish needle), Bidens frondosa (beggar’s tick), Bidens cernua (nodding beggarticks), and ornamental taxa such as Bidens ferulifolia and Bidens coronata. Some species are cultivated in gardens for their showy blooms, while others are considered weeds in agricultural settings.

Uses: Several Bidens species have traditional medicinal uses in various cultures, and some are grown as ornamentals. In some regions, certain taxa are invasive and can impact local ecosystems or agriculture.