Corylus avellana

Corylus avellana, the common hazel, is a species of flowering plant in the birch family Betulaceae. The shrubs usually grow 3–8 metres (10–26 feet) tall. The nut is round, in contrast to the longer filbert nut. Common hazel is native to Europe and Western Asia. The species is mainly cultivated for its nuts. The name 'hazelnut' applies to the nuts of any species in the genus Corylus, but in commercial contexts usually describes C. avellana. This hazelnut or cob nut (sometimes cobnut), the kernel of the seed, is edible and used raw, roasted, or ground into a paste. Historically, the shrub was an important component of the hedgerows used as field boundaries in lowland England. The wood was grown as coppice, with the poles used for wattle-and-daub building and agricultural fencing.

Description

A small deciduous tree up to 7 m high. It spreads to 3-5 m across. The stem is erect, with smooth, brown bark and hairy twigs. The trees sucker a lot, which produces a clumpy bush. The leaves are rounded, tapering to a point, with a heart shaped base. They are 10 cm long, and dull, dark green. The edges of the leaves have saw-like teeth. The leaves are hairy. Male and female flowers are separate, on the one tree. Male flowers are greenish-yellow stalks, like cat's tails. They are 8 cm long and hang downwards. The female flowers are very small, and in groups of four. The fruit are brown nuts 2 cm across. A green husk covers the nut, but then shrinks to allow the nut to darken and ripen. Plants within the Hazel nut group hybridise easily, giving rise to new kinds.

Edible Uses

The seed can be eaten raw or roasted and is used in breads, cakes, biscuits, and sweets. It is an excellent nut for eating out of hand and can also be blended into a plant milk. The seed is rich in oil and ripens in mid to late autumn; it will likely need protection from squirrels. Stored unshelled in a cool place, nuts keep for at least 12 months. A clear yellow edible oil pressed from the seed is used in salad dressings and baking. Per 100g dry weight, the seed provides 650 calories and contains: water 0%, protein 16g, fat 60g, carbohydrate 20g, fibre 4g, ash 2.8g, calcium 250mg, phosphorus 400mg, iron 4mg, sodium 2.1mg, potassium 900mg, thiamine (B1) 0.3mg, riboflavin (B2) 0.5mg, niacin 5.3mg, and vitamin C 6mg.

Traditional Uses

The nuts are eaten raw. They are also roasted and used in bread, cakes, and confectionary. The seeds are eaten both raw and dried. The kernels have a fatty oil which is edible. The male flowers are eaten. The leaves are used for sarma in Turkey. They are rolled around a filling of rice or minced meat.

Medicinal Uses

The bark, leaves, catkins, and fruits are all sometimes used medicinally, with astringent, diaphoretic, febrifuge, nutritive, and odontalgic properties. The seed is stomachic and tonic. The oil has a gentle but consistent and effective action against threadworm or pinworm infection in babies and young children.

Known Hazards

None known

Distribution

A temperate climate plant. They are very frost resistant. They need a certain minimum cold requirement for good production of nuts, so are basically unsuited to the tropics. They need 800-1600 hours of chilling, about the same as apples. They grow in light, well-drained soils, in a protected, partly shaded position. They are drought tender. The flowers can withstand frosts down to -8°C and the wood down to -20°C or -30°C. It suits hardiness zones 4-8. Arboretum Tasmania. Hobart Botanical Gardens.

Where It Grows

Albania, Andorra, Armenia, Asia, Australia, Austria, Azerbaijan, Balkans, Belarus, Belgium, Bosnia, Britain, Bulgaria, Canada, Caucasus, Central Asia, China, Colombia, Czech Republic, Denmark, Estonia, Europe*, Finland, France, Georgia, Germany, Greece, Hungary, India, Iran, Iraq, Ireland, Italy, Kazakhstan, Kosovo, Latvia, Lithuania, Macedonia, Mediterranean, Mexico, Middle East, Netherlands, North Africa, North America, Norway, Pacific, Papua New Guinea, PNG, Poland, Portugal, Romania, Russia, San Marino, Scandinavia, Serbia, Sicily, Slovakia, Slovenia, South America, Spain, Sweden, Switzerland, Syria, Tajikistan, Tasmania, Turkey, Türkiye, Ukraine, USA, Yugoslavia,

Cultivation

An easily grown plant, it succeeds in most soils, but is in general more productive of seeds when grown on soils of moderate fertility. It does less well in rich heavy soils or poor ones. Does well in a loamy soil. Very suitable for an alkaline soil, but it dislikes very acid soils. Succeeds in a pH range 4.5 to 8.5, but prefers a range of 5 to 7. Plants are fairly wind tolerant. A very hardy plant, succeeding in all areas of Britain. The flowers, however, are produced in late winter and early spring and can be damaged by heavy frosts at this time. A parent, together with C. maxima, of many cultivated forms of filberts and cob nuts. There are many named varieties. Plants are self-fertile but a more certain crop is obtained if more than one cultivar is grown. The main difference between cob nuts and filberts is that the husk of a filbert is longer than the seed and often completely encloses it, whilst the husk on a cob nut is shorter than the seed. Squirrels are a major pest of this plant, often decimating the crop of nuts. Often grown as a coppiced shrub in woodlands, the stems have a variety of uses. Members of this genus bear transplanting well and can be easily moved even when relatively large. A food plant for the caterpillars of many lepidoptera species. A clumping plant, forming a colony from shoots away from the crown but with a limited spread. Most Corylus species are not self-fertile and require cross-pollination from another variety to produce nuts. Hazelnuts are typically harvested in late summer to early autumn, when the nuts have matured and fallen from the trees. Hazels flower in late winter to early spring, with male catkins producing pollen before the female flowers emerge. Corylus species are considered medium to fast-growing, reaching a height of about 3 to 6 meters (10 to 20 feet) within 5 to 10 years, depending on the specific variety and growing conditions.

Propagation

Seed is best sown as soon as it is harvested in autumn in a cold frame, germinating in late winter or spring. Stored seed should be pre-soaked in warm water for 48 hours, then given 2 weeks of warm stratification followed by 3–4 months of cold stratification; it germinates in 1–6 months at 20°C. When large enough to handle, prick seedlings out into individual pots and grow on in a cold frame or sheltered spot outdoors through their first winter, then plant out in late spring or early summer. Layering in autumn is easy and takes about 6 months. Division of suckers in early spring is very easy; divisions can be planted straight into permanent positions.

Other Uses

Hazels work well in agroforestry systems as hedging, windbreaks, or for erosion control, and can be intercropped with other plants to benefit soil health and biodiversity. The seed contains up to 65% of a non-drying oil used in paints and cosmetics. Whole seeds can be used to polish and oil wood, giving an easy application and a good finish. Finely ground seeds are used as an ingredient in cosmetic face masks. Plants grown as a tall hedge should be left untrimmed or only lightly trimmed if a seed crop is wanted. Bark and leaves are a source of tannin. The wood is soft, easy to split, and not very durable but is beautifully veined; it is used for inlay work, small furniture, hurdles, wattles, basketry, and pea sticks. Twigs are used as dowsing rods. The wood yields good quality charcoal valued by artists. Hazels produce wind-pollinated catkins that are not rich in nectar but do provide pollen that some insects utilise. The nuts are a valuable food source for birds, small mammals, and insects, and the dense foliage provides shelter and nesting habitat, with leaf litter supporting a variety of organisms. Rough bark and dense foliage also offer overwintering sites for invertebrates.

Production

Nuts are produced 3-4 years after planting. Layered plants produce nuts in 2-3 years. Yields of 4-6 kg of nuts per tree, are average. Nuts fall when mature. Nuts store well. They should be kept dry and cool.

Other Information

It is a cultivated plant. It is sold in local markets. Seeds have been introduced into Papua New Guinea for trial plantings only and are not really a suitable plant for the country.

Notes

There are about 15 Corylus species.

Nutrition

Synonyms

Also Known As

Alun, Aryekh, Aryeshnik, Avellana, Avellano, Basurrek, Bindak, European filbert, European hazelnut, Findak, Findik, Funduk, Hassel, Hazelnoot, Lazdas, Lazdynas, Leithi, Leska, Lesnik, Lieska, Lijeska, Ljathi, Magyarofa, Mogyorofa, Monyaro, Navadna leska, Nisore, Nocella, Nocciolo, Oriesky, Oryekh, Oulanio, Pahklipuu, Sarapuu, Tkhili, Tkhleni, Urretxa

References (88)

• Bianchini, F., Corbetta, F., and Pistoia, M., 1975, Fruits of the Earth. Cassell. p 192
• Bodkin, F., 1991, Encyclopedia Botanica. Cornstalk publishing, p 287
• Bremness, L., 1994, Herbs. Collins Eyewitness Handbooks. Harper Collins. p 100
• Brickell, C. (Ed.), 1999, The Royal Horticultural Society A-Z Encyclopedia of Garden Plants. Convent Garden Books. p 304
• Brouk, B., 1975, Plants Consumed by Man. Academic Press, London. p 216

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