Hazel - Species

Species

Corylus has 14–18 species. The circumscription of species in eastern Asia is disputed, with WCSP and the Flora of China differing in which taxa are accepted; within this region, only those taxa accepted by both sources are listed below. The species are grouped as follows:

• Nut surrounded by a soft, leafy involucre, multiple-stemmed, suckering shrubs to 12m tall
  • Involucre short, about the same length as the nut
    • Corylus americana—American hazel, eastern North America
    • Corylus avellana—Common hazel, Europe and western Asia.
    • Corylus heterophylla—Asian hazel, Asia
    • Corylus yunnanensis—Yunnan hazel, central and southern China
  • Involucre long, twice the length of the nut or more, forming a 'beak'
    • Corylus colchica—Colchican filbert, Caucasus
    • Corylus cornuta—Beaked hazel, North America
    • Corylus maxima—Filbert, southeastern Europe and southwest Asia
    • Corylus sieboldiana—Asian beaked hazel, northeastern Asia and Japan (syn. C. mandshurica)
• Nut surrounded by a stiff, spiny involucre, single-stemmed trees to 20–35 m tall
  • Involucre moderately spiny and also with glandular hairs
    • Corylus chinensis—Chinese hazel, western China
    • Corylus colurna—Turkish hazel, southeastern Europe and Asia Minor
    • Corylus fargesii—Farges' hazel, western China
    • Corylus jacquemontii—Jacquemont's hazel, Himalaya
    • Corylus wangii—Wang's hazel, southwest China
  • Involucre densely spiny, resembling a chestnut burr
    • Corylus ferox—Himalayan hazel, Himalaya, Tibet and southwest China (syn. C. tibetica).

Several hybrids exist, and can occur between species in different sections of the genus, e.g. Corylus × colurnoides (C. avellana × C. colurna). The oldest confirmed hazel species is Corylus johnsonii found as fossils in the Ypresian-age rocks of Ferry County, Washington, USA.