The generic name refers to the same character; Bidens comes from the Latin bis ("two") and dens ("tooth").

[6][7] Bidens is closely related to the American genus Coreopsis, and the genera are sometimes difficult to tell apart; in addition, neither is monophyletic.

[13] Bidens are zoochorous; their seeds will stick to clothing, fur or feathers, and be carried to new habitat.

Several Bidens species are used as food by the caterpillars of certain Lepidoptera, such as the noctuid moth Hypercompe hambletoni and the brush-footed butterfly Vanessa cardui, the painted lady.

Native Hawaiians drink a special tea out of their leaves (known collectively as koʻokoʻolau)[14] back when they were abundant in Hawaii.