Corylus avellana: Everything You Need to Know About the Common Hazelnut

Corylus avellana is the botanical name for the common hazelnut — the native shrub or small tree of European woodlands and hedgerows, and the species from which virtually all cultivated hazelnut and cobnut varieties have been selected. Understanding the species helps you understand why garden varieties behave the way they do and what they need to thrive.

Natural Range and Habits

Corylus avellana is native across Europe, western Asia, and into North Africa. In Britain it is one of the most widespread native shrubs, growing as an understorey plant in oak and ash woodland, as a hedgerow species, and on scrubland across a wide range of soil types and climates. In its natural form it is a multi-stemmed deciduous shrub or small tree growing to five or six metres, producing numerous stems from a permanent woody base called a stool. It is long-lived — a hazelnut stool can persist for centuries — and extraordinarily regenerative after cutting.

The Species and Its Variants

Wild Corylus avellana produces small roundish nuts with a relatively shallow husk. Centuries of selection have produced cultivated forms with much larger nuts, thicker shells, and deeper husk coverage. Named garden varieties of C. avellana include 'Cosford', 'Nottingham', 'Webb's Prize Cob', 'Merveille de Bollwiller', and many others. There are also ornamental selections including 'Contorta' (Harry Lauder's walking stick, with twisted stems) and 'Purpurea' (with purple foliage), though these are generally less productive fruiting plants than the straight species selections.

Relationship to Filbert

Corylus avellana (hazelnut, cobnut) is closely related to Corylus maxima (filbert). The key distinction is the husk: in C. avellana the husk is shorter than the nut; in C. maxima the husk fully encloses and extends beyond the nut. In practice, many commercial cobnuts are hybrids of both species, and the terms are used interchangeably in everyday horticulture.

Wildlife Value

Few native shrubs match Corylus avellana for wildlife value. The catkins provide essential early pollen and nectar for emerging bees, bumblebees, and other pollinators in January and February when almost nothing else is in flower. The nuts are a critical autumn food source for dormice, red squirrels (in areas where they survive), woodpeckers, nuthatches, and numerous small mammals. The dense multi-stemmed structure provides nesting habitat for warblers, finches, and other birds. In a wildlife-focused garden, hazelnut earns its space several times over.

Cultural Uses

Hazelnut has a rich cultural history in Britain and Europe. The coppiced poles were used for hurdles, wattle-and-daub construction, fencing, and basket-making for thousands of years. The nuts have been eaten since Mesolithic times and are found at archaeological sites across the UK. The species was an integral part of the traditional coppice management that once covered much of the British countryside, managed on a seven to twelve year rotation to produce a sustainable supply of poles and nuts alongside a diverse woodland flora beneath the opened canopy.