Corylus – Filbert – Hazel –
There area bout 15 species of deciduous trees and large shrubs, in this genus. They occur in the Northern Hemisphere, usually found in woodland. They have alternate, rounded or oval to ovate, strongly veined, toothed, leaves, sometimes with heart shaped bases. Hazels are grown for their foliage and yellow male pendulous catkins, borne before the leaves in early spring. Female flowers are inconspicuous, small greenish clusters at the branch tips on previous years growth. Male and female flowers grow on the same plant. Cultivars of several species listed below also produce husked, edible nuts. Smaller hazels are best grown in a shrub border, the larger species and cultivars are excellent specimen trees.
Grow in fertile, moist but well drained soil in sun or partial shade, they are ideal for alkaline or chalky soils. Grow variants with colored leaves in full sun.
Prone to powdery mildew, blight, canker, dieback, mushroom root rot, fungal spots, Gymnosporangium rust, bud mites, tent caterpillars, and webworms.
C. colurna – Turkish Hazel – This conical tree from Southeastern Europe and Western Asia grows 70-80′ feet tall and 20-25′ feet wide. It has striking bark with cork-like corrugations. It produces broadly oval, shallowly lobed, dark green leaves, to 5″ long, which are veined and draw to a blunt tip, and turn a light yellow in autumn. In late winter in bears pendent, yellow catkins, 2-3″ long. In autumn it produces edible nuts, enclosed in deeply fringed husks. It is a sun loving tree that thrives in continental climates, hot summers and cold winters.