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Corylus colurna; photograph (c) krickard0505, some rights reserved (CC BY) CC BY(c) krickard0505, some rights reserved (CC BY) · observed growing wild · 2026-09-11

Corylus colurna L.

Turkish hazel; Byzantine filbert; Constantinople-nut; Turkish filbert

Betulaceae · Albania, Bulgaria +8

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Corylus colurna, photograph (c) Fiona Chan-Cary, some rights reserved (CC BY)Corylus colurna, photograph (c) alfanoar, some rights reserved (CC BY)Corylus colurna, photograph (c) Destynnie K. Berard, some rights reserved (CC BY)Corylus colurna, photograph (c) Destynnie K. Berard, some rights reserved (CC BY)Corylus colurna, photograph (c) Destynnie K. Berard, some rights reserved (CC BY)Corylus colurna, photograph (c) Destynnie K. Berard, some rights reserved (CC BY) 62 photographs ›
Habitat figuresfrom few records
Cold floor (1 night in 100)
-11.4°C
Record low -24.9 °C in 44 years, at a typical spot in the range NASA POWER
Warmest month, mean daily high
27°C
Jul and Aug at the habitat CHELSA
Rain a year (median across the range)
747mm
12 months of 25 mm or more in the median year CHELSA
Open-sky light
7–38DLI
Lowest to highest month (DLI) CHELSA
The year in your months, northern hemisphere
  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec
Rain spread: 70% of the median year's rain takes 8 months, so no short rainy season. rain rule, CHELSA
Northern hemisphere unless you set your site. The chart is in the habitat's months.

From few records: 8 records in 8 grid cells. The records.

Summary

Corylus colurna, the Turkish hazel, Byzantine hazel or Constantinople Hazel, is a species of hazel (Corylus) in the birch family (Betulaceae). It is native to the Balkan Peninsula and Western Asia, but has become widely introduced in other areas of Europe as an ornamental, particularly as a street tree. It typically grows 25–30 metres (82–98 ft) tall, with a slender growth form in its youth. Although the nuts are not commercially important, Corylus colurna is commonly used as a single-stemmed, non-suckering rootstock for common hazel (Corylus avellana) scions.

Quoted from Wikipedia, "Corylus colurna", CC BY-SA 4.0.

Cultivation

Seasons

The rain rule reads no short rainy season: 70% of the median year's rain (545 mm of 740 mm) takes 8 months, April to September and November to December. Mean temperature moves 22.0 °C between the warmest and coldest month. Months are the habitat's, northern hemisphere; shifted six months for a southern-hemisphere collection: October to March and May to June.

Rain

740 mm in the median year at the habitat, 545 mm of it April to September and November to December. Wettest month June at 91 mm, driest month February at 40 mm. Across the grid cells of the range the year's total runs 554 mm to 1,179 mm, the 10th to 90th percentile of each cell's own year. The median of the cells' own yearly totals, 747 mm, is the year's rain at the top of the page; the 740 mm here is the median year's, the twelve monthly medians added, which the rain rule reads. Habitat calendar, northern hemisphere; median year across the grid cells of the range, CHELSA.

Light

Open sky over the habitat: 7 to 38 mol/m²/day across the year (daily light integral, median year across the grid cells of the range, CHELSA; the lowest 10th-percentile month across the cells is 7, the highest 90th-percentile month 43).

Warmth and air
Temperature

Coldest: the 1st-percentile night over 44 years at a typical spot in the range is -11.4 °C, the absolute minimum -24.9 °C, 4,043 frost nights in 44 years, 91.9 a year (NASA POWER daily minima). Warmest: the 99th-percentile day is 37.2 °C. Monthly means: the coldest month's mean nightly low -3.0 °C in January (across the grid cells of the range -5.0 °C to -2.8 °C), the warmest month's mean daily high 27.2 °C in July (median year across the grid cells of the range, CHELSA). Cold floor: -11.4 °C, which is the 1st-percentile night over 44 years at a typical spot in the range (NASA POWER).

Humidity

Relative humidity at the habitat: 56 to 65% across the year (monthly means, median year across the grid cells of the range, CHELSA). A figure about the air, saying nothing about how the plant takes water.

How this section is made

Each card states this species' habitat figures with their sources, and what two fixed rules read from them; nothing here says what the plant does, wants or tolerates. The rules · the terms.

Seasons. Read from the median year of CHELSA monthly rainfall and mean temperature across the grid cells of the range: the rain rule takes the smallest set of months carrying 70% of the rain and calls it winter when its mean is more than half a degree below the year's, summer when more than that above, and neither in between; the temperature rule, used only under 120 mm, names the cooler six months when they are at least a degree cooler than the other six. Months are shifted for the other hemisphere only where the temperature curve moves 4 °C or more and the habitat lies 10° or more from the equator. A reading of the curves, not an observation of the plant.

Rain. CHELSA monthly precipitation, median year across the grid cells of the range. The rain that falls where the species is recorded; nothing about how the plant takes water.

Light. CHELSA shortwave radiation at each envelope cell, a daily-mean flux taken to a daily total and converted at 2.07 mol of PAR per MJ. The sky over the habitat, measured; what reaches a plant under a rock, a shrub or a shade cloth is not.

Temperature. NASA POWER daily minima and maxima over 44 years at a typical spot in the range, lapse-corrected +21 m to its elevation; CHELSA monthly means, median year across the grid cells of the range. The cold floor is the 1st-percentile night named in its sentence. Not a measured survival limit for any plant in a pot.

Humidity. CHELSA relative humidity, median year across the grid cells of the range.

Climate across the habitat

From few records: this habitat climate is read from 8 records in 8 grid cells; a page says so under 12 records or 5 cells, and shows the figures as read.

Habitat months, northern hemisphere

Habitat climate of Corylus colurna through the yearWarmest months July and August, mean daily high 27 °C; coldest month January, mean nightly low -3.0 °C; 740 mm of rain in the median year (the twelve monthly medians added). Medians across the range, from CHELSA; the extremes at the edge from NASA POWER. Habitat months, northern hemisphere.-40°-20°0°20°40°frost37.2° 99th-percentile day, NASA POWER-24.9° lowest night in 44 years, NASA POWER°C · day and nightcold quarter0255075100125150mm rainDLI 7–38RH 56–65%JanFebMarAprMayJunJulAugSepOctNovDec
day night rain medians and 10th–90th percentile across 8 habitat cells, CHELSA cold quarter: the three months around the coldest month's mean nightly low extremes over 44 years at a typical spot in the range, from NASA POWER, marked at the edge, in no month DLI, mol/m²/dayRH %each on its own scale
Figures by month
JanFebMarAprMayJunJulAugSepOctNovDec
Day °C4 / 3–46 / 5–611 / 10–1116 / 15–1721 / 19–2225 / 22–2527 / 25–2827 / 24–2822 / 20–2317 / 15–1810 / 9–105 / 4–5
Night °C-3 / -5–-3-3 / -4–-21 / -1–26 / 4–711 / 8–1214 / 12–1516 / 14–1716 / 14–1712 / 10–138 / 6–82 / 1–3-2 / -3–-1
Rain mm47 / 33–7440 / 33–7451 / 38–8859 / 46–8266 / 53–10191 / 66–13567 / 48–11668 / 45–13669 / 42–11857 / 41–12364 / 51–11461 / 51–108
DLI9 / 9–1215 / 14–1822 / 21–2631 / 29–3237 / 34–3838 / 36–4238 / 37–4334 / 31–3825 / 23–2917 / 15–2010 / 9–137 / 7–10
RH %64 / 64–6661 / 60–6258 / 57–6056 / 56–5956 / 55–6057 / 56–6056 / 55–5956 / 55–6058 / 55–6261 / 58–6364 / 61–6565 / 64–67
How this section is made
Each figure is the median across the 8 grid cells holding the 8 in-range records, with the 10th–90th percentile span across those cells after the slash where it differs. A dash is a month one or more of those cells has no figure for in the grid (a variable CHELSA does not carry there), so no median is taken rather than one over fewer cells. Extremes and elevation were read at a typical spot in the range, cell 895:3997 (45.225, 19.875). Over 44 years there: absolute minimum -24.9 °C, 1st-percentile night -11.4 °C, 99th-percentile day 37.2 °C. Normals: CHELSA V2.1 1981–2010 climatology, 0.05° cells (each the mean of ~36 1 km pixels). Across the range: median and 10th–90th percentile of each month across the 8 distinct grid cells holding 8 of the 8 in-range records; extremes and elevation at the typical cell 895:3997 (its coldest month's mean nightly low nearest the median across cells); its position is the cell centre. Extremes: NASA POWER (MERRA-2) daily 1981–2024, cell 45.00_20.000, lapse-corrected +21 m at 6.5 °C/km. Elevation: ETOPO 2022, 128 m (cell mean).

Natural habitat

Native range as published by WCVP; the marker is where the records are densest and decides nothing: the climate was read across the cells of the in-range records placed well enough to read one, not at the marker.
Openly licensed records inside the range, framed on where they fall.
NativeAlbania, Bulgaria, Greece, Romania, Turkey-in-Europe, Yugoslavia, North Caucasus, Transcaucasus, Iran, Turkey · introduced: Great Britain, Austria, Czechoslovakia, Germany, Hungary, Poland, Spain · regions are the level-3 units of the World Geographical Scheme for Recording Plant Distributions, as Kew's World Checklist records ranges, some under historical names such as Yugoslavia or Czechoslovakia (how).
Map marker46.399, 19.114 · in the densest population, 4 records (40% of those in range)
Kew's description“tree” · “temperate” · quoted from WCVP, RBG Kew (CC BY 4.0); not derived here
Evidence usedThe map marker rests on all 10 georeferenced records inside the native range; the climate across the range on the 8 of them placed to within 10 km; the map shows only the 4 openly licensed ones, which alone would put the marker 2350 km away. 204 records outside the WCVP native range not used. Under a dozen records behind the map and the climate. 2 in-range records are placed to worse than 10 km, or with no stated accuracy (admitted only as a person's observation to three decimals), and stay on the map but off the climate.
How this section is made
The map marker: the openly licensed record nearest the middle of the densest 1° population of the 10 in-range records; it decides nothing. Records outside the native range, living specimens and records marked introduced are not used; which records count.

Photographs

Corylus colurna, photograph 1did not loadCorylus colurna, photograph 2did not loadCorylus colurna, photograph 3did not loadCorylus colurna, photograph 4did not loadCorylus colurna, photograph 5did not loadCorylus colurna, photograph 6did not load

Photographs: (c) Fiona Chan-Cary, some rights reserved (CC BY); (c) alfanoar, some rights reserved (CC BY); (c) Destynnie K. Berard, some rights reserved (CC BY) (4).

Similar habitat climate The 6 nearest by mean daily high, mean nightly low and rain, month by month. How.

Tilia tomentosa Tilia tomentosa Silver lime Photo: CC BY, Oleksandr ShynderSyringa vulgaris Syringa vulgaris Common lilac Photo: CC0, author not statedCrocus flavus Crocus flavus Yellow crocus Photo: CC BY, ajottKnautia macedonica Knautia macedonica Macedonian scabious Photo: CC0, author not statedCrataegus nigra Crataegus nigra Hungarian thorn Photo: CC BY, Oleksandr ShynderHibiscus trionum Hibiscus trionum Bladder ketmia Photo: CC BY-SA, Tony Rebelo

Other Corylus 12 in the reference

Corylus americana Corylus americana American hazelnut Photo: CC BY, Shelby Lyn SandersCorylus avellana Corylus avellana Hazel Photo: CC0, author not statedCorylus chinensis Corylus chinensis Chinese Hazlenut Photo: CC BY, Jean-Pol GRANDMONT Corylus × colurnoides Betulaceae Corylus cornuta Corylus cornuta Beaked hazel Photo: CC BY, Rachel StringhamCorylus fargesii Corylus fargesii Betulaceae Photo: CC BY, Tie Guy II on FlickrCorylus ferox Corylus ferox Himalayan hazel Photo: CC BY, Kristof ZyskowskiCorylus heterophylla Corylus heterophylla Siberian filbert Photo: CC BY, Tatyana PetrenkoCorylus jacquemontii Corylus jacquemontii Indian Tree Hazel Photo: CC BY-SA, Dinesh Valke from Thane, IndiaCorylus maxima Corylus maxima Filbert Photo: CC BY, Dawid JuszczakCorylus sieboldiana Corylus sieboldiana Japanese hazel Photo: CC BY, Станислав ЧувановCorylus yunnanensis Corylus yunnanensis Yunnan Hazel Photo: CC0, Daderot

Names & registers

Also known as Corylus abchasica; Corylus arborescens; Corylus avellana f. glomerata; Corylus avellana var. glomerata; Corylus avellana var. macrochlamys and 17 more. (GBIF Backbone)

GBIFPOWOIPNIWFOWikidataWikipediaiNaturalist

The record

Family
Betulaceae
Described by
L.
Native to
Albania, Bulgaria, Greece +7
Wild records
10 in range · 4 open

Every figure here is derived from public data by a stated rule and names its source; nothing about this species is written for its page by a person or by AI, apart from the marked, credited quotations. How →

Where this page came from built 2026-10-21
GBIF species record gbif.species answeredasked 2026-10-21
GBIF synonyms gbif.synonyms answeredasked 2026-10-21
GBIF common names gbif.vernacular answeredasked 2026-10-21names fetched 2026-10-21
WCVP native range wcvp.distribution answeredas of 2026-06-04
GBIF occurrence records gbif.occurrences answeredas of 2026-10-21GBIF occurrence download https://doi.org/10.15468/dl.hbdw64, of 2026-10-21; 27 records within 1 km of a botanic garden, herbarium or zoo left out (19 at a botanic garden or arboretum, 3 at a herbarium, 5 at a zoo; Wikidata's list)
Habitat climate climate answeredasked 2026-10-21
Daily extremes (NASA POWER) climate.extremes answeredasked 2026-10-21NASA POWER (MERRA-2) daily 1981–2024, cell 45.00_20.000, lapse-corrected +21 m at 6.5 °C/km
Wikidata wikidata answeredasked 2026-10-21
Wikipedia wikipedia answeredasked 2026-10-21
iNaturalist photographs, wild inat.photos.wild answeredasked 2026-10-22from iNaturalist's open data of 2026-09-27: research-grade observations with an open-licence photograph, the 24 whose photographs iNaturalist received last (the open data holds no votes); filled 2026-10-22
iNaturalist photographs, cultivated inat.photos.cultivated not asked
GBIF media gbif.media answeredasked 2026-10-21
OpenAlex papers openalex not askednot yet asked for this reference; a later fill takes the papers from OpenAlex's snapshot

Every source is recorded as having answered, reported nothing, refused, failed, not been asked, or answered twice where one answer is taken (“not taken: two items answered”), and, for a source asked when this page was built, when: the figures are as the source held them that day; a source read from a file (Kew's World Checklist, a GBIF download) says "as of" the file's day instead; a row carried from an earlier build of the page names that build instead. Only “nothing to report” is ever shown as an absence. Records came from 36 datasets via GBIF.org; each carries its own licence.

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