The Common Hazel (Corylus avellana) is a species of hazel native to Europe and Asia. It is typically a shrub reaching 3 - 8 m tall, but can reach 15 m. The leaves are deciduous, rounded, 6 - 12 cm long and across, softly hairy on both surfaces, and with a double-serrate margin.
The flowers are produced very early in spring before the leaves and are monoecious, with single-sex catkins, the male pale yellow and 5 -12 cm long, the female very small and largely concealed in the buds, with only the bright red 1 - 3 mm long still visible. The fruit is a nut, produced in clusters of one to five together, each nut held in a short leafy involucre ('husk') which encloses about three quarters of the nut. The nut is roughly spherical to oval, 15 - 25 mm long and 12 - 20 mm broad, yellow-brown with a pale scar at the base. The nut falls out of the involucre when ripe, about 7 - 8 months after pollination.
Cultivation and uses
The Common Hazel is an important component of the hedgerows that were the traditional field boundaries in lowland England. The wood was traditionally grown as coppice, the poles cut being used for wattle-and-daub building and agricultural fencing.
Common Hazel is cultivated for its nuts in commercial orchards in Turkey, Italy, Iran and Caucasus. The name "hazelnut" applies to the nuts of any of the species of the genus Corylus. This hazelnut or cobnut, the kernel of the seed, is edible and used raw or roasted, or ground into a paste. The seed has a thin, dark brown skin which has a bitter flavour and is sometimes removed before cooking. Hazelnuts are extensively used in confectionery to make praline and also used in combination with chocolate for chocolate truffles and products such as Nutella.
Hazelnut is popular as a coffee flavouring, especially in the form of Hazelnut latte. Hazelnut-flavoured coffee seems (to many users) to be slightly sweetened and less acidic, even though the nut is low in natural saccharine. The reason for such perception is not yet understood, but might be due to synergistic interaction with components of coffee.