About 15 species of deciduous, tall shrubs or small trees. Leaves alternate, in 2 rows, usually ovate to obovate, often double serrate. Flowers monoecious (male and female flowers on the same plant), pendulous male catkins in groups of 2-5, female catkins terminal on lateral buds, red stigmas prominent. Fruit, nut, surrounded an involucre of 2 enlarged floral bracts. Native to northern temperate zones.
Corylus: classical Latin name.