Vegetative parts have milky latex that may be inconspicuous or obvious. Leaves are alternate and commonly cordate in outline, but vary to hastate, oblong, or linear. Margins are unlobed or divided into palmate or pinnate divisions. Petioles vary from absent to longer than the leaf blades and are channeled on the upper surface. Inflorescences may be terminal, axillary or in both positions.
Inflorescences vary from being solitary flowers to complex clusters derived from dichasia.
From the basic 3-flowered dichasium, monochasia have arisen in several lineages. Flowers have five free, overlapping sepals, five fused petals, five separate stamens alternating with the petals, and one pistil. Anthers dehisce longitudinally, but twist into a spiral in Merremia , Operculina and their relatives. Fruits are often capsular, but utricular fruits or berries also occur. Seeds vary from 1-4, through abortion, and have large, curved or folded embryos.