03/18/2024

Turkish Filbert

In our continuing effort to promote tree benefits through research, technology, and education, the Ohio Chapter International Society of Arboriculture (ISA) provides Tree-of-the Month articles.  This month’s tree is Corylus colurna, commonly known as Turkish Filbert.

 

SPECIES:  As the common name implies, Turkish filbert is not native to Ohio or North America.  But, because of its unique growing characteristics it is increasingly being planted in our urban forests, and is regularly used by municipal arborists as a street tree, especially for “difficult” sites.

Turkish filbert (Corylus colurna), sometimes called Turkish hazelnut, naturally occurs in mixed temperate forests from Romania, through the Balkans, northern Turkey, Transcaucasia, and Northern Iran.  It has a pyramidal shape with a strong central leader and a horizonal branch structure.  The tree withstands air pollution, compacted soils, high winds, heat and cold, is pH adaptable, and once established is quite drought tolerant.  Add the fact that it is non-suckering, and you can see why municipal arborists confidently include this tree as part of their diversified urban forests.

LEAF:  The deciduous bright glossy green leaves of Turkish filbert are alternately arranged on its twigs.  These broad simple leaves are 3 to 6” long by 3 to 6” wide, doubly serrated with a tapered point, and heart-shaped base.  Deep veins give it a somewhat corrugated appearance.  Its fall color is an unexceptional yellow.      

TWIG AND BUDS:  The thick slightly zigzagged young twigs can be hairy before become grayish brown and corky with age.  Turkish filbert buds are alternately arranged, large (1/3 of an inch), with a brown to greenish-yellow color.        

BARK:  Turkish filbert bark is light gray to brown.  With age, it becomes corky and furrowed giving it an interesting winter appearance. 

FLOWERS:  Turkish filbert is monoecious, with male and female flowers present on the same plant, but in different locations.  While the reddish female flowers are difficult to discern from a distance, the cluster of 2 to 3” long yellowish male catkins provide an early March treat. 

FRUIT OR SEEDS:  The genus name Corylus is derived from the Greek word korylos or korys meaning helmet, which refers to the unique covering enclosing the nut.  These nuts occur in clusters of 3 to 6 which are submerged in a frilly medusa-like husk which matures from a green to brown color.  Although edible, because of their size and difficulty to extract, nuts are normally left to small mammals, especially squirrels.

MATURE HEIGHT:  Turkish filbert is generally considered a medium size tree that slowly grows to a height of 40 to 50’, with a branch spread of roughly 25–35’.  According to the Ohio Department of Natural Resources’ Champion Tree registry, Ohio’s largest Turkish filbert resides in Franklin County and measures 74’ in height, with a 47’ crown spread, and a trunk circumference of 98”.

SHAPE:  Turkish filbert has a tight pyramidal shape with a strong trainable central leader and horizontal branch structure.  Its architecture not only gives Turkish filbert a formal appearance but also makes it quite wind resistant.

CULTIVAR:  The Purple Leaf Turkish filbert, Corylus colurna ‘Purple Leaf’, has similar characteristics to Turkish filbert, but as the name implies, it boasts attractive deep purple leaves with a slight tinge of green.

COMMENTS:  For urban trees to effectively bestow the essential quality of life functions we all want and require, they first must survive and thrive in often harsh sites.  Municipal arborist constantly seek trees that can tolerate heat, cold, drought, pollution, wind, pests, and variable pH soils, while simultaneously and significantly contributing to our urban forest canopy.  Turkish filbert is just this type of tree.   

"Turkish Filbert is one of those great shade trees that I wonder why isn’t planted more often.  They are really tough and can grow in most places, even tree wells in our business districts.  Everything about Turkish Filbert has texture; the leaves, the bark, even its catkins.  I recommend Turkish Filbert to the southwest Ohio communities I serve, but it is good State-wide as a reliable approach to address environmentally harsh sites as well as helping diversify our forest canopy coverage."  ODNR, Division of Forestry Regional Urban Forester Wendi Van Buren

​Tree Selection Tips
The Ohio Chapter ISA recommends working with an ISA Certified Arborist when selecting or caring for any tree in your landscape. To better guide you on the vital plant information for the American Sweet Gum use our friendly user's guide below:

Genus	Corylus
Plant Family	Betulaceae (birches, alders, and hornbeams)
Life cycle	Perennial woody
Origin	Southwester Europe to Western Asia
Habitat	Full Sun
Tree form	Straight trunk with pyramidal shape
Does it produce shade?	Yes
Soil	Moist well-drained soils, but once established will tolerate a wide range of soils
Bloom season	Usually starting in March
Fruit/Seed	Editble nut, about 1/2 inch diameter
Plant height	40-50 feet
Plant spread	25-35 feet
Growth rate	Slow to Medium
Suitable for planting under or near electric (utility)	No
Potential Concerns	None.

Written by Drew Todd and reviewed by Mark A. Webber, BCMA, CPH, LTE,  MArborA, OCMNT, RCA, TPAQ, TRAQ

 

Photograph sources Drew Todd 2024