The hazelnut tree, scientifically known as Corylus avellana, is a deciduous tree or shrub native to Europe and parts of Asia. It typically grows between 10 to 20 feet tall and produces round, edible nuts called hazelnuts. The tree thrives in well-drained soil and prefers a sunny location, making it a popular choice for gardens and orchards. Hazelnut trees are known for their attractive, heart-shaped leaves and catkins, which are the tree's flowers. They usually bear fruit in late summer or early autumn. Besides their culinary uses, hazelnuts are also valued for their oil, which is used in cooking and cosmetics.