Hazelnuts come from the Hazel (Corylus) tree, and are also called “cobnuts” or “filbert nuts.” The tree is native to the Northern Hemisphere, has rounded leaves with serrated edges, and very small pale yellow or red flowers that bloom in spring.
The nuts themselves grow on the trees in husks, then fall out when ripe, about 7-8 months after pollination. The kernel is edible in many ways—raw, roasted, minced, sliced, powdered, or ground into a paste. Hazelnuts are used to make praline, Frangelico liqueur, hazelnut butter, and pastes (like Nutella), and are often added to candies and truffles. The oil is also used for cooking.