{{Short description|Species of tree native to Europe and Asia}} {{Speciesbox |image = Corylus colurna subadriatic dinaric mountains Orjen.JPG |image_caption = Turkish hazel on Orjen, Bosnia and Herzegovina |status = LC |status_system = IUCN3.1 |status_ref = <ref name="IUCN">{{cite journal | last=Shaw | first=Kirsty | title=Turkish Hazel ''Corylus colurna'' | journal=IUCN Red List of Threatened Species | date=2014-08-01 | url=https://www.iucnredlist.org/species/194668/2356927 | access-date=2025-12-29 | page=}}</ref> |genus = Corylus |species = colurna |authority = L. }}
'''''Corylus colurna''''', the '''Turkish hazel''',<ref name="IUCN"/> is a deciduous tree native to Eurasia.
==Distribution and habitat== It is native to southeast Europe and southwest Asia, from the Balkans through northern Turkey to northern Iran.<ref name="POWO">{{cite web | title=''Corylus colurna'' L. | website=Plants of the World Online | url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:295453-1 | access-date=2025-12-29}}</ref>
==Description== It is a large species of hazel, reaching {{convert|25|m|0|abbr=on}} tall,<ref name=Rushforth>{{cite book | last=Rushforth | first=Keith | title=Trees of Britain and Europe | publisher=Trafalgar Square Publishing | publication-place=London | date=1999 | isbn=0-00-220013-9 | pages=190, 621–622}}</ref> exceptionally to {{cvt|33|m|0}} tall,<ref name="MT">{{cite web |last1=Todorov |first1=Atanas |title=Turkish Hazel west of Uzunalak, Kipilovo, Sliven, Bulgaria |url=https://www.monumentaltrees.com/en/bgr/sliven/kotel/38551_uzunalak/72461/ |website=Monumental Trees |access-date=28 December 2025}}</ref> with a stout trunk up to {{cvt|1|m|ft|0}} in diameter,<ref name=Rushforth/> rarely to {{cvt|1.6|m|ft|0}}.<ref name="MT"/> The crown is slender and conical in young trees, becoming broader and irregular with age. The bark is pale grey-buff, with a thick, corky texture. On young trees, the main limbs are quite small in diameter in relationship to the straight trunk, and arise at almost a 90-degree angle. This makes the tree suitable for urban conditions and helps maintain a symmetrical crown which is popular with landscape architects.<ref name="auto">{{cite web|first=Edward and Dennis|last=Gilman and Watson|title= ''Corylus colurna'' Fact Sheet| publisher=University of Florida |year=1993 |url=http://hort.ifas.ufl.edu/database/documents/pdf/tree_fact_sheets/corcola.pdf}}</ref>
thumb|left|Twig in January with male (yellowish-brown) and female (red) catkins The leaves are deciduous, rounded, {{Convert|7–13|cm|in|1}} long and {{cvt|6|–|14|cm|in|1}} across, softly hairy on both surfaces, and with a coarsely double-serrate to shallowly lobed margin.<ref name=Rushforth/> The buds are ovoid, pale brown. The flowers are produced in late winter or early spring before the leaves; the species is monoecious, with the individual catkins single-sex, but both sexes on the same tree (and often on the same twig); the male catkins are conspicuous, pale yellow and 5–10 cm long, the female very small and inconspicuous, largely concealed in the buds, with only the bright red 1–3 mm long styles visible.
The fruit is a nut and may be known as the Turkish hazel nut, Turkish nut, or Constantinople nut. It is about 1–2 cm long, surrounded by a thick, softly spiny and bristly involucre (husk) 3 cm diameter,<ref name=Rushforth/> which encloses all but the tip of the nut; the nuts are borne in tight clusters of 3–8 together, with the involucres fused at the base. The fruit matures in September to October and is edible. Its taste is very similar to common hazel, but it is smaller and has a thicker nut shell.<ref name="Corylus colurna">{{cite web|title=''Corylus colurna''|publisher=University of Connecticut|url=http://www.hort.uconn.edu/plants/c/corcol/corcol1.html|access-date=2014-02-25|archive-url=https://web.archive.org/web/20140301222951/http://www.hort.uconn.edu/Plants/c/corcol/corcol1.html|archive-date=2014-03-01|url-status=dead}}</ref> 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 <ref>Turkish Hazel. (n.d.) The Great Soviet Encyclopedia, 3rd Edition. (1970-1979). Retrieved 26 February 2014 from http://encyclopedia2.thefreedictionary.com/Turkish+Hazel</ref>
=== Root === ''Corylus colurna'' has fibrous roots.<ref>{{cite web|title=Guidelines for Tree Planting on the Right of Way|url=http://www.citywindsor.ca/residents/parksandforestry/Urban-Forest/Documents/Guidelines_for_Tree_Planting_o.pdf|publisher=City of Windsor}}</ref> 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.<ref>Nikolva, M. (2007). Experimental results on variety-rootstock interaction in filbert culture. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 35(2), 82-87.</ref>
==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''.<ref>{{cite web| title=Turkish hazelnut| publisher=The Morton Arboretum| year=2013| url=http://www.mortonarb.org/trees-plants/tree-plant-descriptions/turkish-hazelnut}}</ref>
''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.<ref>Phillips, L. (2002, July). Turkish Hazelnut. (Tree of the Month). Arbor Age, 22(7), 38. Retrieved from http://go.galegroup.com/ps/i.do?id=GALE%7CA89379137&v=2.1&u=sunycesfsc&it=r&p=PPAG&sw=w&asid=48a6ee3d38e80930f3a4add21f707a6d</ref> ''Corylus colurna'' has received the Royal Horticultural Society's Award of Garden Merit.<ref name="RHSPF">{{cite web |url=https://www.rhs.org.uk/Plants/4517/Corylus-colurna/Details |title=''Corylus colurna'' |website=www.rhs.org |publisher=Royal Horticultural Society |access-date=12 April 2020}}</ref>
===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.<ref>L. (2013). Corylus colurna turkish hazel pfaf plant database. Retrieved from http://www.pfaf.org/user/plant.aspx?LatinName=Corylus colurna</ref>
==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.<ref name="auto" /> Other landscape uses for ''C. colurna'' are for fruit, difficult and dry sites, and naturalistic areas.<ref name="Corylus colurna" />
==Gallery== <gallery> File:Törökmogyoró.jpg|Foliage and immature fruit File:Baum Hasel, Corylus colurna 1.JPG|Involucre with ripe nut File:Involucre d'un noisetier de Bysance.jpg|Bristly involucre File:Corylus colurna0.jpg|A young Turkish hazel showing the narrow conical crown File:2015-05 ND-41 Baumhasel E-Leithe.jpg|Older specimens become broader, but often retain a good shape </gallery>
==Related species== Similar species ''Corylus jacquemontii'', once considered as a variety of ''Coryllus colurna'', is found growing wild in the forests of Western Himalayan range in the north Indian state of Himachal Pradesh particularly in the temperate regions of districts of Kullu, Shimla, Kinnaur district and Chamba district.<ref>Gupta and Sharma(2016).'''Site and stand characteristics of hazelnut bearing forests in temperate region of Himachal Pradesh'''.International Journal of Farm Sciences'. Vol:6,Issue:1.http://www.indianjournals.com/ijor.aspx?target=ijor:ijfs&volume=6&issue=1&article=040</ref><ref>[https://www.vulhm.cz/files/uploads/2022/08/LP_1_2022.pdf Novotný et. al.: Katalog taxonů introdukovaných dřevin s potenciálem lesnického využití na stanovištích s nižší dostupností vláhy, 2022]</ref>
==References== {{Reflist}}
==External links== {{Commons category|Corylus colurna}} * [http://www.euforgen.org/species/corylus-colurna/ ''Corylus colurna''] {{Webarchive|url=https://web.archive.org/web/20191216013608/http://www.euforgen.org/species/corylus-colurna/ |date=2019-12-16 }} - information, genetic conservation units and related resources. European Forest Genetic Resources Programme (EUFORGEN)
{{Taxonbar|from=Q148939}} {{Authority control}}
colurna Category:Trees of Western Asia Category:Trees of Pakistan Category:Trees of Turkey Category:Trees of Azerbaijan Category:Plants described in 1753 Category:Botanical taxa named by Carl Linnaeus Category:Flora of Montenegro