Hazel

For other uses, see Hazel (disambiguation).

Hazels
Common hazel (Corylus avellana)
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Fagales
Family: Betulaceae
Subfamily: Coryloideae
Genus: Corylus
L.
Type species
Corylus avellana
Species

See text for species.

Synonyms[1]

Lopima Dochnahl

Young male catkins of Corylus avellana

Hazels are plants of the genus Corylus of deciduous trees and large shrubs native to the temperate Northern Hemisphere. The genus is usually placed in the birch family Betulaceae,[2][3][4][5] though some botanists split the hazels (with the hornbeams and allied genera) into a separate family Corylaceae.[6][7] The fruit of the hazel is the hazelnut.

Hazels have simple, rounded leaves with double-serrate margins. The flowers are produced very early in spring before the leaves, and are monoecious, with single-sex catkins. The male catkins are pale yellow and 5–12 centimetres (2–4+3⁄4 inches) long, and the female ones are very small and largely concealed in the buds, with only the bright-red, 1-to-3 mm-long styles visible. The fruits are nuts 1–2.5 cm (1⁄2–1 in) long and 1–2 cm diameter, surrounded by an involucre (husk) which partly to fully encloses the nut.[4]

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.[4]

The pollen of hazel species, which are often the cause for allergies in late winter or early spring, can be identified under magnification (600×) by their characteristic granular exines bearing three conspicuous pores.[8]

  1. ^ Kew World Checklist of Selected Plant Families
  2. ^ Germplasmgobills Information Network: Corylus Archived 2009-01-14 at the Wayback Machine
  3. ^ Chen, Zhi-Duan; Manchester, Steven R; Sun, Hai-Ying (August 1999). "Phylogeny and evolution of the Betulaceae as inferred from DNA sequences, morphology, and paleobotany". American Journal of Botany. 86 (8): 1168–1181. doi:10.2307/2656981. ISSN 0002-9122. JSTOR 2656981. PMID 10449397.
  4. ^ a b c Rushforth, K. (1999). Trees of Britain and Europe. Collins ISBN 0-00-220013-9.
  5. ^ Huxley, A., ed. (1992). New RHS Dictionary of Gardening. Macmillan ISBN 0-333-47494-5.
  6. ^ Bean, William Jackson (1976). Trees and Shrubs Hardy in the British Isles. Vol. 1. Taylor, George (8th ed.). London: J. Murray. ISBN 0719517907. OCLC 103403.
  7. ^ Erdogan, V.; Mehlenbacher, S. A. (2002). "Phylogenetic analysis of hazelnut species (Corylus, Corylacae) based on morphology and phenology". Sist. Bot. Dergisi. 9: 83–100.
  8. ^ Airy, Hubert (1874). "Pollen-grains in the Air". Nature. 10 (253): 355. Bibcode:1874Natur..10..355A. doi:10.1038/010355b0. S2CID 4077214.