(Corylus avellana, Corylus maxima)
Other Names: Filbert, Cobbnut, Avellana, Noisette
The Common Hazel (Corylus avellana) is a shrub that typically reaches 3-8 m tall, but can reach 15 m on occasion. 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 styles 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. It is readily distinguished from the closely related Filbert (Corylus maxima) by the short involucre; in the Filbert the nut is fully enclosed by a beak-like involucre longer than the nut.
Hazelnuts are eaten raw or toasted and used in cakes and desserts. Hazelnuts are extensively used in confectionery to make praline and also used in combination with chocolate for chocolate truffles.Hazelnut is also becoming popular as an addition to the range of coffees drunk by the modern café society with Hazel latte becoming popular. The popularity of Hazelnut liqueur, based on a vodka, is now increasing especially in eastern Europe. Hazelnut oil, pressed from hazelnuts, is strongly flavoured and used as a cooking oil.
Hazelnuts are rich in protein and unsaturated fat. Moreover, they contain significant amounts of thiamine and vitamin B6, as well as smaller amounts of other B vitamins.
Hazelnuts are deciduous, requiring a cool winter to provide a sufficient chill to break the dormancy of the flowering and vegetative buds. This crop is best suited to temperate climate, where summers are not excessively hot. An average annual rainfall of over 900mm is desirable, with supplementary irrigation to overcome moisture deficits in the years of below average rainfall. In the winter and early spring, the female flowers tolerate temperatures down to -9º C.
Hazelnuts require a very well-drained soil and trees should not be located where the soil is poorly drained, shallow, too heavy or too light. Most of a hazelnut tree's roots are found in the first metre of soil, but soils must be sufficiently deep to allow active root systems to penetrate 2 - 3 metres. Soil for the hazelnuts should be in the slightly acidic to neutral range.
Propagation is accomplished largely by simple layerage, but traditionally was by removing suckers from existing trees. However, suckers do not produce as efficiently as layers. Semi-hardwood cuttings can also be used for propagation