Hazel
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214799783
2008-05-25T09:39:30Z
Raven in Orbit
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Reverted edits by [[Special:Contributions/75.89.70.218|75.89.70.218]] ([[User talk:75.89.70.218|talk]]) to last version by 84.219.5.119
{{otheruses4|the type of tree}}
{{Taxobox
| name = Hazel
| image = Hazel Catkins.jpg
| image_width = 240px
| image_caption = Flowering Common Hazel in early spring
| regnum = [[Plant]]ae
| divisio = [[flowering plant|Magnoliophyta]]
| classis = [[dicotyledon|Magnoliopsida]]
| ordo = [[Fagales]]
| familia = [[Betulaceae]]
| genus = '''''Corylus'''''
| genus_authority = [[Carolus Linnaeus|L.]]
| subdivision_ranks = Species
| subdivision = See text
}}
The '''hazels''' ('''''Corylus''''') are a genus of [[deciduous]] [[tree]]s and large [[shrub]]s native to the temperate northern hemisphere. The genus is usually placed in the [[birch]] family [[Betulaceae]],<ref name=grin>Germplasm Resources Information Network: [http://www.ars-grin.gov/cgi-bin/npgs/html/genus.pl?2962 ''Corylus'']</ref><ref name=chen>Chen, Z.-D. et al. (1999). Phylogeny and evolution of the Betulaceae as inferred from DNA sequences, morphology, and paleobotany. ''Amer. J. Bot''. 86: 1168–1181. Available [http://www.amjbot.org/cgi/content/full/86/8/1168?ck=nck#F5 online.]</ref><ref name=rushforth>Rushforth, K. (1999). ''Trees of Britain and Europe''. Collins ISBN 0-00-220013-9.</ref><ref name=rhs>Huxley, A., ed. (1992). ''New RHS Dictionary of Gardening''. Macmillan ISBN 0-333-47494-5.</ref> though some botanists split the hazels (with the [[hornbeam]]s and allied genera) into a separate family Corylaceae.<ref name=bean1>Bean, W. J. (1976). ''Trees and Shrubs Hardy in the British Isles'' 8th ed., vol. 1. John Murray ISBN 0-7195-1790-7.</ref><ref name=>Erdogan, V. & Mehlenbacher, S. A. (2002). Phylogenetic analysis of hazelnut species (Corylus, Corylacae) based on morphology and phenology. ''Sist. Bot. Dergisi'' 9: 83–100.</ref>
[[Image:TurkHazel.jpg|left|thumb|Leaves and nuts of Turkish Hazel: note the spiny involucres (husks) surrounding the nuts]]
They have simple, rounded [[leaf|leaves]] with double-serrate margins. The [[flower]]s are produced very early in spring before the leaves, and are [[plant sexuality|monoecious]], with single-sex [[catkin]]s, the male pale yellow and 5–12 cm long, the female very small and largely concealed in the buds, with only the bright red 1–3 mm long [[Carpel|style]]s visible. The [[seed]]s are [[Nut (fruit)|nuts]] 1–2.5 cm long and 1–2 cm diameter, surrounded by an involucre (husk) which partly to fully encloses the nut.<ref name=rushforth/>
The shape and structure of the involucre, and also the growth habit (whether a tree or a suckering shrub), are important in the identification of the different species of hazel.<ref name=rushforth/>
Hazels are used as food plants by the [[larva]]e of various species of [[Lepidoptera]]; see [[list of Lepidoptera that feed on hazels]].
==Species==
There are 14–18 species of hazel. The circumscription of species in eastern Asia is disputed, with the ''Kew Checklist'' and the ''Flora of China'' differing in which taxa are accepted; within this region, only those taxa accepted by both sources are listed below.<ref name=kew>Kew Checklist: [http://www.kew.org/wcsp/qsearch.do?plantName=Corylus&page=quickSearch ''Corylus'']</ref><ref name=rushforth/><ref name=foc>Flora of China: [http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=108088 ''Corylus'']</ref><ref name=fna>Flora of North America: [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=108088 ''Corylus'']</ref> The species are grouped as follows:
* Nut surrounded by a soft, leafy [[involucre]]. Multi-stemmed, suckering [[shrub]]s to 12m tall.
**Involucre short, about the same length as the nut.
*** ''[[Corylus americana]]'' — American Hazel. Eastern North America.
*** ''[[Corylus avellana]]'' — Common Hazel. Europe and western Asia.
*** ''[[Corylus heterophylla]]'' — Asian Hazel. Asia.
*** ''[[Corylus yunnanensis]]'' — Yunnan Hazel. Central and southern China.
**Involucre long, twice the length of the nut or more, forming a 'beak'.
*** ''[[Corylus colchica]]'' — Colchican Filbert. Caucasus.
*** ''[[Corylus cornuta]]'' — Beaked Hazel. North America.
*** ''[[Corylus maxima]]'' — Filbert. Southeastern Europe and southwest Asia.
*** ''[[Corylus sieboldiana]]'' — Asian Beaked Hazel. Northeastern Asia and Japan (syn. ''C. mandshurica'').
* Nut surrounded by a stiff, spiny involucre. Single-stemmed trees to 20–35 m tall.
**Involucre moderately spiny and also with glandular hairs.
*** ''[[Corylus chinensis]]'' — Chinese Hazel. Western China.
*** ''[[Corylus colurna]]'' — Turkish Hazel. Southeastern Europe and Asia Minor.
*** ''[[Corylus fargesii]]'' — Farges' Hazel. Western China.
*** ''[[Corylus jacquemontii]]'' — Jacquemont's Hazel. Himalaya.
*** ''[[Corylus wangii]]'' — Wang's Hazel. Southwest China.
**Involucre densely spiny, resembling a chestnut burr.
*** ''[[Corylus ferox]]'' — Himalayan Hazel. Himalaya, Tibet and southwest China (syn. ''C. tibetica'').
Several [[Hybrid (biology)|hybrids]] exist, and can occur between species in different sections of the genus, e.g. ''[[Corylus × colurnoides]]'' (''C. avellana'' × ''C. colurna'').
==Uses==
[[Image:Hazelnuts.jpg|thumb|[[Hazelnuts]]]]
The nuts of all hazels are edible. The Common Hazel is the species most extensively grown for its nuts, followed in importance by the Filbert. Nuts are also harvested from the other species, but apart from the Filbert, none is of significant commercial importance.<ref name=rhs>Huxley, A., ed. (1992). ''New RHS Dictionary of Gardening''. Macmillan ISBN 0-333-47494-5.</ref>
A number of [[cultivar]]s of the Common Hazel and Filbert are grown as [[ornamental plant]]s in [[garden]]s, including forms with contorted stems (''C. avellana'' 'Contorta', popularly known as "[[Harry Lauder]]'s walking stick" from its gnarled appearance); with weeping branches (''C. avellana'' 'Pendula'); and with purple leaves (''C. maxima'' 'Purpurea').
==References==
{{reflist}}
[[Category:Corylus| ]]
[[Category:Betulaceae]]
[[bg:Леска]]
[[de:Hasel (Botanik)]]
[[et:Sarapuu]]
[[el:Φουντουκιά]]
[[es:Corylus]]
[[eo:Avelujo]]
[[fr:Noisetier]]
[[hsb:Lěšćina]]
[[it:Specie di Corylus]]
[[ka:თხილი]]
[[la:Corylus]]
[[lt:Lazdynas]]
[[nl:Corylus]]
[[ja:ハシバミ属]]
[[nn:Hasselslekta]]
[[pl:Leszczyna]]
[[pt:Corylus]]
[[ru:Лещина]]
[[sq:Corylus]]
[[fi:Pähkinäpensaat]]
[[sv:Hassel]]
[[tr:Fındık]]