Leaves simple or compound, the leaflets leathery, papery or succulent, smooth-edged, toothed or lobed. Flower heads are solitary or, more often, in few to many-flowered terminal clusters. Fruits, achenes, are brown, gray or black, slender, twisted, coiled or winged. Unlike its mainland relatives, endemic Bidens species are barbless. Half are endemic to single islands and half are found on two or three islands.
Some species are fairly common and a few are restricted to small populations.
Bidens micrantha Gaud. The leaves of some species were used for medicinal tea by Hawaiians. Do not transport and cultivate Bidens not endemic to an island to prevent the possibility of accidental cross-pollination. Upright, bushy shrubs 1.5-3.0 feet tall. Leaves compound, the leaflets extremely variable in shape.