The Filbert (Corylus maxima) is a species of hazel native to southeast Europe and southwest Asia. It is a deciduous shrub 6-10 m tall, with stems up to 20 cm thick. The leaves are rounded, 5-12 cm long by 4-10 cm broad, with a coarsely double-serrated margin. The flowers are wind-pollinated catkins produced in late winter; the male (pollen) catkins are pale yellow, 5-10 cm long, the female catkins bright red, only 2-3 mm long. The fruit is a nut produced in clusters of 1-5 together; each nut is 1.5-2.5 cm long, fully enclosed in a 3-5 cm long tube-like involucre (husk).

The Filbert is similar to the related Common Hazel (C. avellana), differing in having the nut more fully enclosed by the tube-like involucre; this feature is shared by the Beaked Hazel (C. cornuta) of North America, and the Asian Beaked Hazel (C. sieboldiana) of eastern Asia.

Uses

The nut is edible, and very similar to the Common Hazel nut. Filberts are sometimes grown in orchards for the nuts, but much less often than the Common Hazel.

The purple-leaved cultivar Corylus maxima 'Purpurea' is a popular ornamental shrub in gardens,