Filbert, a flavorful nut with a brittle shell. Most cultivated filberts are obtained from hybrids of the European hazel, giant hazel, and cobnut trees. The leading producers of filberts are Turkey, Italy, Spain, and the United States. Most of the United States crop comes from Oregon.
Trees bearing filberts belong to the genus Corylus of the birch family, Betulaceae. The European hazel is C. avellana pontica; giant, C. maxima; cobnut, C. avellana grandis.