Common hazel (Latin: Córylus avellána) is a species of deciduous woody shrubs and trees of the genus Hazel (Corylus) of the Birch family (Betulaceae). In nature, the range of the species covers all of Europe, the Caucasus and the Middle East. The northernmost natural habitats of common hazel, where it forms the most extensive thickets, are located in Norway, beyond the Arctic circle, in the Prestegordsskugen nature reserve, located near 68° s. s., and some less significant areas are even slightly North of this reserve. It is cultivated everywhere. It grows in broad-leaved, mixed and coniferous forests in the form of undergrowth, often on the edges, in the mountains it occurs up to the border of forest vegetation, in the Caucasus it rises to 2100-2300 m above sea level. In the steppe zone, it is distributed in oak forests, thickets of shrubs, along the banks of rivers and lakes, on the slopes of hills and in steppe gullies. Sometimes it forms clean thickets. It has an exceptional ability to reproduce by root offspring, which makes it very quickly occupies forest clearings and is considered a weed in forestry. Shade-tolerant, avoids open and hot southern slopes. Shrub 2-5 m high, sometimes growing tree-like; crown ovate or flat-spherical. The bark of the trunks is smooth, light, brownish-gray, cross-striped; the shoots are brownish-gray, pubescent, glandular-hairy. The root system is superficial and powerful. First, the taproot develops, and by the third year, lateral, powerful, knotty roots are formed. One of the lateral roots is usually more powerful and longer. Fruits are crowded in two or five, sometimes single. The fruit wrapper is light green, velvety pubescent, broad-lobed or bell-shaped, open, almost the same length as the nut, and consists of two irregularly dissected lobed leaflets. The nut is almost spherical or somewhat elongated, 18 mm long, 13-15 mm in diameter, light to dark brown. There are 870 fruits in 1 kg. The average yield of 1 ha of garden in 600 bushes is about 900 kg. Life expectancy is up to 100 years. The plant has been used and cultivated since ancient times as a nut-bearing plant. Hazelnuts contain about 65 % fat, about 16 % protein, and about 3.5 % sugar; they are used in the confectionery and food industry; halva, sweets, chocolate and other products are prepared from them; dry ones — nutritious flour, and young ones — milk. Almond-like oil is squeezed out of the seeds — which is one of the best vegetable oils.