Corylus colurna Seeds | Turkish Hazel
LATIN NAME: Corylus colurna
COMMON NAME: Turkish Hazel, Byzantine Hazel, Constantinople Hazel
Plant Profile
This is the largest member of the genus, capable of reaching the height of a small oak with a straight central stem and a dense, regular crown. The leaves are broad and rounded with a soft double serration, opening early and turning a warm yellow in autumn. As the trunk ages, ridges of corky tissue rise along it in vertical plates, a texture that shows to best advantage in winter, and the bark stays pale grey where other street trees go black with soot.
The nuts sit in clusters of up to eight, each wrapped in a husk whose edges are cut into deep, ragged fringe. That fringed, bristly husk is the quick way to tell a Turkish hazel from a common filbert, whose husk is shorter and smoother and often covers only the base of the nut. The nuts themselves have a notably thick shell, which protects them from birds and gives them a long storage life, though it also makes cracking them by hand a chore and small hammers a necessity.
Because it does not throw up suckers, this species is grafted or used as a rootstock under named filbert varieties to produce orchard trees that can be managed as clean single stems and harvested from the ground by machine. Its deep, sturdy root also gives the orchard drought tolerance and anchorage on windy sites. Street planting is the other great use: the species tolerates compacted soil, reflected heat, air pollution and hard pruning better than almost any other broadleaf tree of its size, and it is widely planted along avenues in central and northern Europe.
Science & Biotechnology
A peculiar line of research has followed the hazels, and it is not about the nuts. Tissues of Corylus, including the Turkish hazel, produce taxane diterpenoids, the same family of compounds that includes paclitaxel, the anticancer drug originally extracted from the Pacific yew. Leaves, husks and cultured callus have all been screened, and the finding matters because yew trees are slow, scarce and protected. Some of the hazel taxanes are the simpler intermediates of the pathway rather than the finished drug, but the work has made the genus a laboratory curiosity as well as an orchard crop.
Hazelnut is among the foods most often responsible for reactions in Europe, and the proteins responsible have names that a grower should know. A seed storage globulin and a small lipid-transfer protein carry most of the risk, and both survive roasting, which is why cooked nuts are not automatically safe. There is also cross-reaction with birch pollen that shows up as an itchy mouth after eating raw nuts. Anyone breeding or planting hazels for a public site should treat the allergy as a real design constraint rather than a footnote.
Uses & Benefits
Hazels are wind-pollinated and monoecious, carrying separate male and female flowers on the same tree. The male catkins form in autumn, hang all winter and release clouds of pollen on the first mild days of the new year; the female flowers are tiny buds from which a tuft of crimson stigmas protrudes at exactly the same moment. The species is self-incompatible, with a self-recognition system that stops a tree fertilising its own flowers, so a lone specimen sets few nuts and a planted group sets many. The Turkish hazel flowers early even by hazel standards, which makes it valuable as a pollen source for other hazels.
Growing from Seed
Young trees drive a strong taproot straight down, and a seedling left too long in a shallow bed ends up with a coiled root and a permanent check to its growth. Sow or plant out young, into deep containers or a well-prepared open site, and move the tree only while it is still small. Once established, the tree is drought-tolerant and needs no irrigation, though the first two seasons need regular water while the roots reach down into the subsoil.
Hazel nuts are orthodox but short-lived if dried out, so treat them like acorns rather than like beans. Sow fresh nuts in autumn in an open bed, or keep them in damp sand in a cool shed and sow in late winter before they begin to sprout. Depth of two to three times the nut’s own size suits them, and a covering of mesh stops mice and jays from clearing the row overnight. A well-grown seedling reaches planting size in a few seasons.
Our Take
Plant this one for the long view: a single specimen on a lawn, well staked, with the trunk clear of branches to head height so that the fluting can be seen. In a hedge or a nuttery, set it beside Corylus avellana, the common filbert, to provide the cross-pollination both need, and compare the two husks when the nuts ripen. Corylus chinensis is the Chinese tree hazel of the same style and is worth a trial in milder districts, while Carpinus betulus, the hornbeam, is the betulaceous tree I would use to fill the same urban role on heavier clay.
Related Reading
Continue exploring with these related plants: