Filbert

It is a deciduous shrub 6–10 metres (20–33 feet) tall, with stems up to 20 centimetres (8 inches) thick. The leaves are rounded, 5–12 cm (2–4+3⁄4 in) long by 4–10 cm (1+1⁄2–4 in) 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 (2–4 in) long, while the female catkins are bright red and only 1–3 mm (1⁄16–1⁄8 in) long. The fruit is a nut produced in clusters of 1–5 together. Each nut is 1.5–2.5 cm (1⁄2–1 in) long, fully enclosed in a 3–5 cm (1+1⁄4–2 in) long, tubular involucre (husk).

Similar species. The filbert is similar to the related common hazel, C. avellana, differing in having the nut more fully enclosed by the tubular involucre. This feature is shared by the beaked hazel C. cornuta of North America, and the Asian beaked hazel C. sieboldiana of eastern Asia.

The species is native to southeastern Europe and southwestern Asia, from the Balkans to Turkey.

The purple-leaved cultivar C. maxima 'Purpurea' is a popular ornamental shrub in gardens. The filbert nut is edible and is very similar to the hazelnut (cobnut). Its main use in the United States is as large filler (along with peanuts as small filler) in most containers of mixed nuts. Filberts are sometimes grown in orchards for the nuts, but much less often than the common hazel.