Winter sap contains a high concentration of stored sugars. Fossil plant parts are common in the Eocene. Flowers are small and in inflorescences of corymbs, panicles, racemes, or umbels. Hypogynous or perigynous. Fruit a winged schizocarp or samara.
Seed is solitary and without endosperm.
Placentation is axile. Habit is as shrubs or trees. Opposite and deciduous or evergreen.