Corylus maxima, the filbert, is a species of hazel in the birch family Betulaceae, native to southeastern Europe and southwestern Asia.

It is a deciduous shrub 6–10 m (20–33 ft) tall, with stems up to 20 cm (8 in) thick.

[3][4] The filbert is similar to the related common hazel, C. avellana, differing in having the nut more fully enclosed by the tubular involucre.

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

Use in this manner has faded partly due to the efforts of Oregon's hazelnut growers to brand their product to better appeal to global markets and avoid confusion.