Hazel

Hazel
Corylus avellana

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Hazel belongs to the genus Corylus and is a member of the Birch family (Betulaceae).

Hazel (Corylus avellana ) is a deciduous tree growing to around 10m and flowering January to April.

Lifespan: The normal lifespan is around 70–80 years, but coppicing enables this tree to live to great ages of several hundred years.

 

Characteristics

Hazel can grow as a small tree with a single stem but is more frequently found as a multi-stemmed shrub. It has coppery-brown smooth, peeling bark. Twigs have reddish glandular hairs. Buds are oval, blunt and hairy. Leaves are alternate along the stem; 10cm, round-oval, doubly toothed, downy above and below with a pointed tip. The stalks of the leaves are also hairy.

Hazel is monoecious: both male and female flowers are found on the same tree. Male flowers appear before the leaves and are long (2–8cm) pendulous catkins, yellow, hanging in clusters. Female flowers are small and bud-like with red styles 5mm. Fruits are oval (1–2cm) and hang in groups of one to four, maturing into a nut with a woody shell surrounded by a collar of leafy bracts. Hazel is wind pollinated.

Hazel tree
Hazel leaves

Distribution

Native to the UK and across a wide area of Europe, parts of north Africa and western Asia.

In the UK it is commonly found as an understorey species in lowland oak, ash or birch woodland as well as in scrub and hedgerows.

Hazel has been grown for its wood for centuries using coppicing – a traditional method that involves cutting trees to ground level and allowing them to re-grow, producing multiple long thin stems. It is therefore found growing commonly in this form, particularly in the south of England, and because of the longevity of this method many species of wildlife have become adapted to the coppiced environment.

Older woodland may still comprise ‘coppice with stands’; a mix of coppiced hazel with taller trees such as oak. These were grown together to provide mixed sizes of timber for constructing traditional wooden buildings.

Human value

Hazel timber is pale brown, straight grained and very hard. It is always produced in small diameters.

In the past, hazel was an important tree economically. Coppiced stems were durable and had a variety of uses including wattles for wattle and daub plaster work, hurdles for fencing, thatching spars, wood fuel and charcoal for gun powder.

Today, hazel coppice has become an important management method in wildlife conservation of woodland habitats and is practised at many sites and in restoration schemes to help support some of our rarer native species. The resulting timber is used in many rural crafts.

The nuts are edible, and hazel was also grown in the UK for large-scale nut production until the early 1900s. Cultivated varieties of hazel nuts are still grown in Kent (known as Kentish cobnuts) but most of our hazelnuts are now imported.

Hazel flowers
Hazel leaves close-up

Wildlife value

Hazel is a very valuable tree for wildlife. Its leaves provide food for many moth species, notably the large emerald, small white wave, barred umber and nut-tree tussock moths. Coppice areas of hazel provide open flowery habitats that support many fritillary species of butterfly.

Hazel provides an important food source for the dormouse, both in terms of the insects found upon it (especially caterpillars) and its nuts, which are the main food dormice use to fatten up for hibernation.

Hazel nuts are also eaten by woodpeckers, nuthatches, tits, woodpigeons, jays and other native mammals such as the red squirrel, wood mouse, yellow-necked mouse and bank vole. Hazel flowers provide a vital source of early nectar for many bumble bee species.

Hazel has symbiotic (mutually beneficial) relationships with a number of fungi including the fiery milkcap, which appears in autumn.

Areas of coppiced hazel provide shelter and protection for many ground-nesting birds including several Birds of Conservation Concern (BoCC) noted by the UK Biodiversity Action Plan such as the nightingale, nightjar, yellowhammer and willow warbler.

Many species of wild flower have become adapted to coppice activity and the associated periodic changes in light at the woodland floor. Notable of these are orchids such as early-purple, common twayblade, fly orchid and the greater and lesser butterfly orchids.

Management

Hazel is a hardy, moderately shade tolerant, fast-growing species able to cope in elevations up to 700m above sea level. It thrives best on well-drained, fertile, neutral to calcareous soils. It cannot tolerate water logging or very acidic soils.

Hazel can be grown easily from the seed. The seeds ripen September to October and remain viable for around six months. For larger scale plantings seeds are usually pre-treated and sown in April.

Coppiced hazel is generally cut in rotations of 6–10 years. Harvesting is not advised in early spring or summer due to risk of disturbing nesting birds.

Generally hazel only suffers from minor disease issues such as aphids, gall mites and sawflies. Hazel can be heavily browsed by deer if not protected after coppicing.

Hazel stems

Illustrations © Reader’s Digest Association, Inc.
Photographs © Debbie Cotton