Corylus

The hazel (Corylus) is a genus of deciduous trees and large shrubs native to the temperate Northern Hemisphere. The genus is usually placed in the birch family Betulaceae,[2][3][4][5] though some botanists split the hazels (with the hornbeams and allied genera) into a separate family Corylaceae.[6][7] The fruit of the hazel is the hazelnut.