Corylus colurna, the Turkish hazel,

Description

It is a large species of hazel, reaching tall, exceptionally to tall, with a stout trunk up to in diameter,

thumb|left|Twig in January with male (yellowish-brown) and female (red) catkins

The leaves are deciduous, rounded, long and across, softly hairy on both surfaces, and with a coarsely double-serrate to shallowly lobed margin. They are occasionally gathered from the wild as well as from urban trees, but their small size (smaller than common hazel nuts) and very hard, thick nut shell (3 mm thick) makes them of little or no commercial value. Corylus colurna is however important in commercial hazelnut orchards, as it does not sucker, making it the ideal rootstock on which to graft the nut-bearing common hazel cultivars. Nut production is irregular and occurs every two to three years

Root

Corylus colurna has fibrous roots. The roots are not adventitious, meaning they do not form suckers. This makes C. colurna desirable for grafting on the rootstock over a single stemmed trees. This allows it to be grown in poorer and rocky soils.

Cultivation

Corylus colurna has a medium growth rate. It is occasionally drought tolerant and alkaline soil tolerant. However, it prefers moist, well-drained soil, as well as full sun. Once established C. colurna is tolerant of heat, cold, and drought. There are no serious pests or problems with C. colurna.

Corylus colurna is not easily transplantable and will need extra watering in summer after transplanting. It will take about two years after transplant for the tree to become established and survive on its own. Corylus colurna has received the Royal Horticultural Society's Award of Garden Merit.

Propagation

The most common form of propagation is by seed. It is best sown as soon as it is harvested in autumn in a cold frame. The seed will germinate in late winter or spring. If starting with a stored seed, the seed should be pre-soaked in warm water for 48 hours and then given 2 weeks warm followed by 3 to 4 months cold stratification. This will allow the seed to germinate in 1 to 6 months if kept at 20 °C. Once the seedlings are large enough to handle, pick the seedlings out into individual pots and grow them on in a cold frame or sheltered place outdoors for their first winter. The seedlings can be planted into their permanent positions in late spring or early summer.

Uses

Besides its use as a single-stem rootstock for C. avellana, C. colurna is widely cultivated as an ornamental tree in Europe and North America. It is very tolerant of difficult growing conditions in urban situations, which in recent decades has increased its popularity in civic planting schemes. Turkish hazel makes a good shade tree since it produces dense shade, and its narrow crown and ability to withstand air pollution make it well suited for use as a street tree in urban areas, or a specimen tree in parks. It makes a rather formal statement in the landscape due to the tight, consistently-shaped, narrow crown.

References

  • Corylus colurna - information, genetic conservation units and related resources. European Forest Genetic Resources Programme (EUFORGEN)