Corylus heterophylla, the Asian hazel, is a species of hazel native to eastern Asia in northern and central China, Korea, Japan, and southeastern Siberia. It is a deciduous shrub or small tree growing to 7 m tall, with stems up to 20 cm thick grey bark. The leaves are rounded, 4–13 cm long and 2.5–10 cm broad, with a coarsely double-serrated to somewhat lobed margin and an often truncated apex. The flowers are wind-pollinated catkins; the male (pollen) catkins are pale yellow, 4 cm long, while the female catkins are bright red and only 1–3 mm long. The fruit is a nut produced in clusters of 2–6 together; each nut is 0.7–1.5 cm diameter, partly enclosed in a 1.5–2.5 cm long, bract-like involucre (husk).