are a group of about ten species of small trees or large shrubs that are native to the temperate northern hemisphere. The botanic name of the genus is Corylus
, and it is placed either in the family Betulaceae
The nuts obtained from the species Corylus avellana are the common edible hazelnuts. This large shrub is grown extensively for its nuts. Nuts are also harvested from some of the other species, including the filbert, from the Balkan species Corylus maxima.
Some species, such as the Turkish hazel are cultivated as ornamental trees. A number of ornamental garden forms of the common hazel are found, including forms with contorted stems, with purple leaves, and with weeping branches.
The species include;
- Corylus americana - American hazel, from eastern North America
- Corylus avellana - hazel, from Europe, North Africa and West Asia
- Corylus chinensis - Chinese hazel, from West China
- Corylus colurna - Turkish hazel, from southeastern Europe and West Asia
- Corylus cornuta - Beaked hazel, of eastern North America
- Corylus maxima - filbert, of southeastern Europe
- Corylus sieboldiana - from northeastern Asia and Japan
- Corylus thibetica - Tibetan hazel, from Tibet and China.