Species:
– Genus Corylus includes around 14–18 species
– Taxonomy of hazel species in eastern Asia disputed between different sources
– Hybrids can occur between hazel species in different sections of the genus
– Oldest confirmed hazel species is Corylus johnsonii found as fossils in Washington
– Chilean hazel (Gevuina avellana) is not related to Corylus genus
Ecology:
– At least 21 fungus species have a mutualistic relationship with hazel
– Hazel is a host for rare species like Hypocreopsis rhododendri and Lactarius pyrogalus
– Several rare lichen species depend on hazel trees
– In the UK, five moth species specialize in feeding on hazel
– Animals like red deer, dormouse, and red squirrel eat hazelnuts
Uses:
– Hazelnuts from all hazel species are edible
– Common hazel is extensively grown for nuts, followed by the filbert
– Hazel is used for making wattle, withy fencing, baskets, and coracle boat frames
– Hazel trees can be coppiced for regular harvests
– Hazel is a food plant for larvae of various Lepidoptera species
Culture:
– Celts believed hazelnuts provided wisdom and inspiration
– Ancient tales mention hazel trees and salmon as sources of wisdom
– Hazel branches are believed to offer protection in folklore
– Hazel plays a role in Grimms Fairy Tales like Cinderella
– Fionn Mac Cumhail from Gaelic mythology is associated with hazelnuts
Gallery:
– Farges hazel form
– Male catkins of common hazel
– Female flower of common hazel
– Leaves and nuts with spiny husks of Turkish hazel
– Closeup of male hazelnut flower using autofluorescence microscopy
Hazels are plants of the genus Corylus of deciduous trees and large shrubs native to the temperate Northern Hemisphere. The genus is usually placed in the birch family Betulaceae, though some botanists split the hazels (with the hornbeams and allied genera) into a separate family Corylaceae. The fruit of the hazel is the hazelnut.
| Hazels | |
|---|---|
| |
| Common hazel (Corylus avellana) | |
Scientific classification 
| |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Fagales |
| Family: | Betulaceae |
| Subfamily: | Coryloideae |
| Genus: | Corylus L. |
| Type species | |
| Corylus avellana | |
| Species | |
|
See text for species. | |
| Synonyms | |
|
Lopima Dochnahl | |
Hazels have simple, rounded leaves with double-serrate margins. The flowers are produced very early in spring before the leaves, and are monoecious, with single-sex catkins. The male catkins are pale yellow and 5–12 centimetres (2–4+3⁄4 inches) long, and the female ones are very small and largely concealed in the buds, with only the bright-red, 1-to-3 mm-long styles visible. The fruits are nuts 1–2.5 cm (1⁄2–1 in) long and 1–2 cm diameter, surrounded by an involucre (husk) which partly to fully encloses the nut.
The shape and structure of the involucre, and also the growth habit (whether a tree or a suckering shrub), are important in the identification of the different species of hazel.
The pollen of hazel species, which are often the cause for allergies in late winter or early spring, can be identified under magnification (600×) by their characteristic granular exines bearing three conspicuous pores.