Hazelnut trees, also known as Corylus avellana, are deciduous trees or large shrubs that produce edible nuts called hazelnuts. They typically grow to a height of 10 to 20 feet and thrive in well-drained, loamy soil. These trees are commonly found in temperate regions and prefer full sun to partial shade. The trees produce small, yellow flowers in early spring, which are wind-pollinated. Hazelnuts mature in late summer to early fall, encased in a green husk. Besides their culinary uses, hazelnuts are also valued for their oil and are a source of food for various wildlife species.