Common filbert

<em>Corylus avellana</em> is a deciduous shrub or small tree in the family Betulaceae, order Fagales, commonly known as the common hazel or common filbert. The species is classified as Least Concern on the IUCN Red List, with widespread and stable populations across its native and introduced range. <em>Corylus avellana</em> is native to Europe and western Asia and has been introduced to parts of North America and South America. It is particularly associated with temperate deciduous woodlands, hedgerows, and scrubland across the Mediterranean forests and the Palearctic realm. The species typically forms a multi-stemmed shrub with broad, rounded leaves and catkins that emerge in late winter before the leaves appear, representing one of the earliest flowering events of the temperate year. Hazel nuts produced by this species are an important food source for woodland wildlife including squirrels, dormice, and woodpeckers. The species has been cultivated for centuries for nut production and coppicing. Biological traits of this species remain poorly documented in the scientific literature.