Lianas or vines of forest canopy, open disturbed areas, or savanna vegetations. Cross section with a single or multiple vascular cylinders, often producing milky sap. Stipules minute or small, early deciduous or persistent. Leaves alternate, trifoliolate, pinnately 5-foliolate, biternate, or triternate, or seldom bipinnate. Thyrses axillary or distal, racemose or paniculate, with flowers on lateral cincinni. Flowers zygomorphic; calyx 4-5-merous, the sepals distinct, or the two anterior ones connate to different degrees into a larger sepal; petals 4, distinct with a hood-shaped appendage, larger in postrior petals; disc unilateral, 2- to 4-lobed; stamens 8, the filaments of unequal length, the anthers dorsifixed; ovary 3-locular, the locules with a single ovule. Fruit a schizocarp, splitting into three samaroid mericarps, with a proximal wing. Seeds lenticular to globose, not arillate.
Guianas present, Neotropical present, Northern America, Southern America, northern Argentina present
A Neotropical genus with about 230 species mostly distributed below 1500 m in savannas, dry forest, or open, disturbed habitats from Mexico to northern Argentina, including the West Indies. Eight species in the Guianas.