Common Names in English:
or rarely shrubs
, monoecious, evergreen
or deciduous. Stipules usually early deciduous. Leaves alternate, sometimes false-whorled in Cyclobalanopsis. Inflorescences unisexual
or androgynous with female cupules at the base
of an otherwise male inflorescence. Male inflorescences a pendulous head
or pendulous catkin, sometimes branched; flowers in dense cymules
. Male flower: sepals 4-6(-9), scalelike, connate
; petals absent; filaments
or versatile, opening by longitudinal
slits; with or without a rudimentary
pistil. Female inflorescences of 1-7 or more flowers subtended individually or collectively by a cupule formed from numerous
fused bracts, arranged individually or in small groups along an axis or at base of an androgynous inflorescence or on a separate axis. Female flower: perianth 1-7 or more; pistil 1; ovary inferior, 3-6(-9) -loculed; style and carpels as many as locules; placentation axile
; ovules 2 per locule. Fruit a nut. Seed usually solitary by abortion
(but may be more than 1 in Castanea, Castanopsis, Fagus, and Formanodendron), without endosperm; embryo large.
Seven to 12 genera (depending on interpretation) and 900-1000 species: worldwide except for tropical and S Africa; seven genera and 294 species (163 endemic, at least three introduced ) in China.
Many species are important timber trees. Nuts of Fagus, Castanea, and of most Castanopsis species are edible, and oil is extracted from nuts of Fagus. Nuts of most species of this family contain copious amounts of water soluble tannin. Members of the Fagaceae are the main element of both broad-leaved evergreen and mixed mesophytic forests from 500-3200 m. 
or winter-deciduous, sometimes rhizomatous
buds spheric to ovoid
, all scales
imbricate. Leaves: stipules deciduous and inconspicuous (except in Quercus sadleriana ) . Leaf blade
or unlobed, thin or leathery, margins
, or awned-toothed, secondary veins either unbranched, ± parallel, extending to margin, or branching and anastomosing before reaching margin. Inflorescences unisexual
, in axils of leaves or bud scales, usually clustered at base
of new growth; staminate
inflorescences usually stiff, with terminal cupule and sometimes 1-several sessile, lateral
cupules. Staminate flowers
: sepals connate
; stamens (2-) 6(-12), surrounding tuft of silky
(apparently a reduced pistillode
) . Pistillate flower 1 per cupule; sepals connate; carpels and styles 3(-6) . Fruits: maturation
or biennial; cup
variously shaped (saucer- to cup- or bowl- to goblet-shaped), without indication
, covering base of nut (rarely whole nut), scaly
, scales imbricate or reduced to tubercles
, not or weakly reflexed
, never hooked
; nut 1 per cup, round
, not winged
Species ca. 400: North America, Mexico, West Indies, Central America, South America (Colombia only), Eurasia , n Africa.
Quercus is without doubt one of the most important woody genera of the Northern Hemisphere. Historically, oaks have been an important source of fuel, fodder , and building materials throughout their range . Other products include tannins and dyes, and oak bark and leaves were often used for tanning leather . Acorns were historically an important food for indigenous people in North America, Central America, Europe, and Asia. In some areas, acorn consumption is still important, but in general, because of the intense preparation necessary to remove tannins and strong flavor of acorn products, they have fallen out of use as human food in developed areas. They do remain, however, an important mast for wildlife and domesticated animals in many rural areas.
Among the most important diagnostic characters within Quercus, and particularly the white oak group ( Quercus sect. Quercus), are features of the foliar trichomes . Often these can be seen with a 10× or 15× hand lens ; higher magnifications are sometimes required and are useful particularly when characters for a species or complex are first studied and mastered for later use in the field . Although these microscopic characters may seem intimidating, the alternative characters of leaf shape and dentition, so often used in the field, are unreliable in many cases. The large number of misidentified specimens in herbaria that can be easily identified properly with the use of trichome characters illustrates this point . Additionally, many specimens are encountered, both in field and herbarium , that lack fruit or have only immature fruit. Very few species require mature fruit for proper diagnosis ; most can be adequately identified with a representative selection of mature sun leaves attached, if possible, to twigs with mature buds. The combination of leaf vestiture, form of the margin (entire, lobed, toothed, spinose ), twig vestiture , and bud form and vestiture constitute the majority of diagnostic features minimally required at species level.
Staminate floral and inflorescence characters have not been used to any significant extent in the taxonomy of Quercus . Immature, flowering material is often difficult to identify with certainty, and floral features such as number and form of sepals, number of stamens, and pubescence of flowers or floral rachises seem to vary independently of species affinity within many groups. Because of these problems, descriptions of staminate features are excluded in this treatment as unreliable and of little diagnostic value. When collecting flowering oaks, make a point of gathering fallen fruit and mature leaves carefully from the ground , if available, and revisit such populations again when mature material is available to verify identifications.
The character of acorn maturation in the first year (annual maturation) or second year (biennial maturation) after pollination is commonly used to differentiate major groups within Quercus . All of the North American white oaks have annual maturation; all of the Protobalanus group have biennial maturation; and the vast majority of red oaks have biennial maturation, with one eastern North American and a few western species with annual maturation. In the field, this character can be observed throughout the growing season by examining a sample of twigs from the same tree. If developing fruits exhibit a single size class and are found only on the current year's growth, maturation is annual; if the developing fruits exhibit two size classes with small pistillate flowers on new growth and larger developing fruit on the previous year's twigs, maturation is biennial. In Quercus sect. Protobalanus, biennial maturation may be mistaken for annual maturation because all of the species are fully evergreen, and often the twigs bearing fruit do not produce new growth in the second year after pollination. In such cases, careful examination of a broad sample of twigs from within one tree and throughout a population will verify biennial maturation. Herbarium specimens are sometimes inadequate for this determination.
Hybridization among species of Quercus has been widely documented and even more widely suspected. An astounding number of hybrid combinations have been reported in the literature, and many of these have been given species names , either before or after their hybrid status was known (E. J. Palmer 1948) . Hybrids are known to occur in the wild only between members of the same section, and attempts at artificial crosses between species from different sections or subgenera within Quercus have failed with very few exceptions (W. P. Cottam et al. 1982) .
Hybridization in most cases results in solitary unusual trees or scattered clusters of intermediate individuals (J. W. Hardin 1975) . In some cases, however, populations of fairly broad distribution and extreme variability, often with a majority of intermediate types, may occur. Such instances occur in both the red oak and white oak groups, and to a lesser extent in the Protobalanus group.
When dealing with a suspected hybrid, therefore, one should first consider the possibility of intraspecific variation or environmental plasticity, and then seek parentage among sympatric members of the same section. Because of the almost infinite number of possible hybrid combinations, and the myriad names applied to them, only those that appear to be prominent either locally or in widespread areas are dealt with here. The interested reader is referred to various discussions of oak hybridization in the literature (e.g. , E. J. Palmer 1948; J. W. Hardin 1975) .
- Whittaker & Margulis,1978
- Haeckel, 1866
- Cavalier-Smith, 1981
- Sinnott, 1935 ex Cavalier-Smith, 1998
- Vascular Plants
- Kenrick & Crane, 1997
- Brongniart, 1843
- Takhtajan, 1967
- (Engler, 1892) Takhtajan, 1997
- Order: Fagales () - Engler, 1892
- Superorder: Faganae () - (Engler, 1892) Takhtajan, 1997
- Subclass: Rosidae () - Takhtajan, 1967
- Class: Spermatopsida () - Brongniart, 1843
- Infraphylum: Radiatopses () - Kenrick & Crane, 1997
- Subphylum: Euphyllophytina ()
- Phylum: Tracheophyta () - Sinnott, 1935 ex Cavalier-Smith, 1998 - Vascular Plants
- Subkingdom: Viridaeplantae () - Cavalier-Smith, 1981
- Kingdom: Plantae () - Haeckel, 1866 - Plants
Quercus aegilops brantii (Lindl.) A. Camus • Quercus aegilops persica (Jaub. & Spach) Blakelock • Quercus baneica Djav. -Khoie • Quercus brantii oophora (Kotschy) O. Schwarz • Quercus brantii persica (Jaub. & Spach) O. Schwarz • Quercus brantii var. belangeri (A. Dc.) Zohary • Quercus brantii var. marasiensis Zohary • Quercus brantii var. persica (Jaub. & Spach) Zohary • Quercus globularis Djav. -Khoie • Quercus oophora Kotschy • Quercus persica Jaub. & Spach • Quercus persica var. belangeri A. Dc. • Quercus persica var. longicupulata Djav. -Khoie • Quercus persica var. ovoidea Djav. -Khoie • Quercus persica var. retrosquamata Djav. -Khoie • Quercus saii Djav. -Khoie • Quercus squamulosa Djav. -Khoie
: Lindl. Publication
: Edwards's Bot. Reg. 26(Misc.):
Name Status: Accepted Name .
Last scrutiny: 11-Nov-2003
Members of the genus Quercus
ZipcodeZoo has pages for 400 species, subspecies, varieties, forms, and cultivars in this genus. Here are just 100 of them:
Q. acerifolia (Maple-Leaved Oak) · Q. acuta (Japanese Evergreen Oak) · Q. acutissima (Sawtooth Oak) · Q. acutissima acutissima (Sawtooth Oak) · Q. acutissima 'Gobbler' (Sawtooth Oak) · Q. agrifolia (California Live Oak) · Q. ajoensis (Ajo Mountain Scrub Oak) · Q. alba (Eastern White Oak) · Q. alba 'Brush Creek' (Oak) · Q. alba 'Gatton Grave' (Oak) · Q. alba 'Linclon' (Oak) · Q. aliena (Oriental White Oak) · Q. alnifolia (Golden Oak) · Q. alvordiana (Alvord Oak) · Q. arizonica (Arizona White Oak) · Q. arkansana (Arkansas Oak) · Q. ashei (Ash's Oak) · Q. atlantica (Atlantic Oak) · Q. austrina (Bastard White Oak) · Q. beadlei (Beadle's Oak) · Q. beaumontiana (Beaumont's Oak) · Q. bebbiana (Bebb's Oak) · Q. beckyae (Becky's Oak) · Q. benderi (Bender Oak) · Q. berberidifolia (Scrub Oak) · Q. bernardiensis (Bernard's Oak) · Q. bicolor (Swamp White Oak) · Q. bimundorum (Oak) · Q. blufftonensis (Bluffton's Oak) · Q. boyntonii (Boynton Sand Post Oak) · Q. brantii (Brant's Oak) · Q. brenesii (Roble) · Q. brittonii (Britton's Oak) · Q. buckleyi (Texas Red Oak) · Q. burnetensis (Burnet's Oak) · Q. bushii (Bush's Oak) · Q. byarsii (Byars' Oak) · Q. caduca (Oak) · Q. caesariensis (Caesar Oak) · Q. capesii (Cape Oak) · Q. carmenensis (Mexican Oak) · Q. castaneaefolia (Slender Maori Wrasse) · Q. castaneifolia (Chestnut-Leaved Oak) · Q. cedrosensis (Cedros Island Oak) · Q. cerrioides (Roble Pubescente) · Q. cerris (European Turkey Oak) · Q. chapmanii (Chapman Oak) · Q. chihuahuensis (Chihuahuan Oak) · Q. chrysolepis (Canyon Live Oak) · Q. chrysolepis Liebm. var. chrysolepis Liebm. (Canyon Live Oak) · Q. chrysolepis Liebm. var. nana (Jeps.) Jeps. (Canyon Live Oak) · Q. coccifera (Kermes Shrub Oak) · Q. coccinea (Scarlet Oak) · Q. coccinea var. coccinea Muenchh. (Scarlet Oak) · Q. coccinea var. tuberculata Sarg. (Scarlet Oak) · Q. cocksii (Cocks' Oak) · Q. columnaris (Column Oak) · Q. comptoniae (Compton's Oak) · Q. cornelius-mulleri (Muller Oak) · Q. costaricensis (Roble Negro) · Q. cravenensis (Oak) · Q. deamii (Deam's Oak) · Q. demareei (Oak) · Q. dentata (Daimyo Oak) · Q. dentata dentata (Daimyo Oak) · Q. dentata 'Pinnatifida' (Japanese Emperor Oak) · Q. depressipes (Davis Mountain Oak) · Q. discreta (Discreet Oak) · Q. diversiloba (Manylobed Oak) · Q. dolicholepis (Oak) · Q. douglasii (Blue Oak) · Q. dumosa (Coastal Sage Scrub Oak) · Q. dumosa Nutt. var. dumosa Nutt. (Coastal Sage Scrub Oak) · Q. dumosa Nutt. var. elegantula Jeps. (Coastal Sage Scrub Oak) · Q. dumosa turbinella (Coastal Sage Scrub Oak) · Q. durandii var. sinuata (Bastard White Oak) · Q. durata (Leather Oak) · Q. durata var. gabrielensis (San Gabriel Mountains Leather Oak) · Q. egglestonii (Eggleston's Oak) · Q. ellipsoidalis (Hill's Oak) · Q. emoryi (Blackjack Oak) · Q. engelmannii (Engelmann Oak) · Q. eplingii (Epling's Oak) · Q. exacta (Oak) · Q. faginea (Oak) · Q. falcata (Southern Red Oak) · Q. faxonii (Faxon's Oak) · Q. fernaldii (Fernald's Oak) · Q. fernowii (Fernow's Oak) · Q. filialis (Oak) · Q. floribunda (Mohroo) · Q. fontana (Fontana Oak) · Q. frainetto (Hungarian Oak) · Q. frainetto 'Forest Green' (Italian Oak) · Q. franchetii (Oak) · Q. fusiformis (Escarpment Live Oak) · Q. gambelii (Gambel Oak) · Q. gambelii Nutt. var. bonina Welsh (Gambel Oak) · Q. ganderi (Gander Oak) · Q. garlandensis (Garland Oak)
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- Novon a journal of botanical nomenclature from the Missouri Botanical Garden. 17 2007 St. Louis, MO: Missouri Botanical Garden, url p. 279, p. 437.
- Huang Chengchiu, Chang Yongtian, Hsu Yongchun & Jen Hsienwei. 1998. Fagaceae. In: Chun Woonyong & Huang Chengchiu, eds. Fl. Reipubl. Popularis Sin. 22: 1-332.
- Hunt, D. M. 1989. A Systematic Review of Quercus Series Laurifoliae, Marilandicae and Nigrae. Ph.D. dissertation. University of Georgia.
- Muller, C. H. 1961. The live oaks of the series Virentes. Amer. Midl. Naturalist 65: 17-39.
- Muller, C. H. 1951. The oaks of Texas. Contr. Texas Res. Found., Bot. Stud. 1: 21-323.
- Nixon, K. C. 1993. Infrageneric classification of Quercus (Fagaceae) and typification of sectional names. Ann. Sci. Forest. 50(suppl.1): 25-34.
- Nixon, K. C. 1993b. The genus Quercus in Mexico. In: T. P. Ramamoorthy et al., eds. 1993. Biological Diversity of Mexico: Origin and Distribution. New York. Pp. 447-458.
- Palmer, E. J. 1948. Hybrid oaks of North America. J. Arnold Arbor. 29: 1-48.
- Sargent, C. S. 1918. Notes on North American trees. I. Quercus. Bot. Gaz. 65: 423-459.
- Tillson, A. H. and C. H. Muller. 1942. Anatomical and taxonomic approaches to subgeneric segregation in American Quercus. Amer. J. Bot. 29: 523-529.
- Trelease, W. 1924. The American oaks. Mem. Natl. Acad. Sci. 20: 1-255.
- Brands, S.J. (comp.) 1989-present. The Taxonomicon. Universal Taxonomic Services, Zwaag, The Netherlands. Accessed March 27, 2012.
Accessed through GBIF Data Portal December 05, 2007:
- Tiroler Landesmuseum Ferdinandeum, Tiroler Landesmuseum Ferdinandeum
- Biodiversity Heritage Library NamebankID: 2670501
- Catalogue of Life Accepted Name Code: Kew-171850
- Global Biodiversity Information Facility Taxonkey: 14245234
- Globally Unique Identifier: urn:lsid:ipni.org:names:295874-1
- GRIN Nomen Number: 30647
- Integrated Taxonomic Information System (ITIS) Taxonomic Serial Number (TSN): 506533
- International Plant Names Index (IPNI) ID: 295874-1
- U.S.D.A. Plant Symbol: QUPE3
- Zipcode Zoo Species Identifier: 59214
- Chengjiu Huang, Yongtian Zhang & Bruce Bartholomew "Fagaceae". in Flora of China Vol. 4 Page 314. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
- Kevin C. Nixon "Quercus". in Flora of North America Vol. 3. Oxford University Press. Online at EFloras.org. [back]