See text for species.
SynonymsLopima Dochnahl
Young male catkins of Corylus avellanaHazels are plants of the genus Corylus of deciduous trees and large shrubs native to the temperate ...
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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 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.