**Botanical Description and Taxonomy**:
– Common hazel is a shrub reaching 3–8 meters tall, with deciduous rounded leaves that are 6–12 cm long.
– Flowers are monoecious, wind-pollinated catkins, and the fruit is a nut roughly spherical to oval, 15–20mm long.
– The scientific name avellana originates from the town of Avella in Italy, selected by Linnaeus from Leonhart Fuchss De historia stirpium commentarii insignes.
– The name is derived from Pliny the Elder’s encyclopedia Naturalis Historia.
**Distribution and Ecology**:
– Common hazel is found from Ireland to Iberia, Italy, Greece, Turkey, and Cyprus, extending north to central Scandinavia and east to the central Ural Mountains.
– It is also present in the Caucasus, northwestern Iran, and provides food for various animals like Lepidoptera.
– The roots of hazel trees are used as hosts for mycorrhizal fungi, and the Black Truffle is found on the roots in the Mediterranean.
**Biochemistry and Health Benefits**:
– Hazelnuts are recognized as heart-healthy foods by the FDA and are associated with a low risk of cardiovascular disease and cancer.
– They contain phenolics like catechin, gallic acid, and flavonoids, providing various health benefits.
– Hazelnut leaves and foliar buds also contain bioactive phenols.
**Cultivation and Hazelnut Byproducts**:
– Over 400 hazel cultivars exist, including Barcelona, Butler, and Ennis, with some being hybrids between common hazel and filbert.
– Commercial hazelnuts are mainly propagated from root sprouts, and ornamental cultivars like Contorta have received awards.
– Hazelnut byproducts, including shells and skins, contain antioxidant phytochemicals and can be utilized for various applications.
– Hazelnut oil extraction methods and nutritional value of byproducts are also significant in cultivation practices.
**Research and Miscellaneous Information**:
– Studies focus on hazelnut kernel antioxidants, hazel leaves as sources of antimicrobial compounds, and the nutritional value of hazelnut byproducts.
– Publications cover hazelnut cultivars, lipid and phenolic fractions, and the world hazelnut situation according to USDA.
– Additional information includes NatureServe data on Corylus avellana, RHS Dictionary of Gardening entry, and general hazelnut nutrition facts.