Herbs climbing, with abundant milky juice. Leaves spirally arranged, estipulate. Cymes axillary, branched, ± scorpioid, ebracteate. Flowers very small. Sepals (4 or)5, coherent at base. Petals (4 or)5, coherent at base. Stamens (4 or)5, epipetalous. Disk absent. Ovary superior, 1-loculed, apically with 2 pendulous ovules; styles 2, dissimilar, 1 longer and thicker, cylindric or subclavate, persistent on fruit, other style shorter and thinner, with capitate stigma. Fruit a 2-winged samara, indehiscent, flat, 2-seeded; embryo minute, in fleshy endosperm.