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Quercus nigra

(Water Oak)


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Common Names

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Click on the language to view common names.

Common Names in Arabic:

سنديان أسود

Common Names in English:

Water Oak, Possum Oak

Common Names in French:

Chêne Gris

Common Names in Latvian:

Melnais ozols


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Family Fagaceae

Trees 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 erect or pendulous catkin, sometimes branched; flowers in dense cymules . Male flower: sepals 4-6(-9), scalelike, connate or distinct ; petals absent; filaments filiform ; anthers dorsifixed 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. [1]

Genus Quercus

Trees or shrubs , evergreen or winter-deciduous, sometimes rhizomatous . Terminal buds spheric to ovoid , terete or angled , all scales imbricate. Leaves: stipules deciduous and inconspicuous (except in Quercus sadleriana ) . Leaf blade lobed or unlobed, thin or leathery, margins entire, toothed , 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 lax , spicate ; pistillate 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 hairs (apparently a reduced pistillode ) . Pistillate flower 1 per cupule; sepals connate; carpels and styles 3(-6) . Fruits: maturation annual or biennial; cup variously shaped (saucer- to cup- or bowl- to goblet-shaped), without indication of valves , 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 in cross section , not winged . x = 12.

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) .[2]

Physical Description

Species Quercus nigra

Trees , deciduous or tardily deciduous, to 30 m. Bark grayish black, fissures irregular, shallow, inner bark pinkish. Twigs dark red-brown, 1.5-2.5 mm diam., glabrous . Terminal buds reddish brown, ovoid , 3-6.5 mm, puberulent throughout, occasionally densely pubescent on apical 2/3. Leaves: petiole 2-9 mm, glabrous. Leaf blade distinctly obtrullate, rarely elliptic or merely obovate , widest near apex, 30-120(-160) × 15-60(-70) mm, base attenuate or cuneate, rarely rounded , margins entire with 1 apical awn or with 2-3 shallow lobes and 2-5 awns (leaves on juvenile or 2d-flush growth may be deeply lobed with more awns), apex obtuse to blunt or rounded; surfaces abaxially glabrous except for minute or conspicuous axillary tufts of tomentum , veins rarely raised, adaxially glabrous with secondary veins somewhat impressed . Acorns biennial; cup saucer-shaped , 2.5-5.5 mm high × 10-18 mm wide, covering 1/4 nut or less, outer surface puberulent, inner surface sparsely to uniformly pubescent, scale tips tightly appressed , acute; nut broadly ovoid, 9.5-14 × 9.5-14.5 mm, often faintly striate , glabrate , scar diam. 6-11.5 mm. [source]

Trees with 3-lobed leaves with attenuate bases have been recognized as Quercus nigra var. tridentifera Sargent. [source]

Quercus nigra reportedly hybridizes with Q. falcata (= Q. × garlandensis E. J. Palmer), Q. incana, Q. laevis (= Q. × walteriana Ashe), Q. marilandica (= Q. × sterilis Trelease), Q. phellos (= Q. × capesii W. Wolf), Q. shumardii (= Q. × neopalmeri Sudworth), and Q. velutina ( Q. × demarei Ashe). In addition, D. M. Hunt (1989) cited evidence of hybridization also with Q. arkansana, Q. georgiana, Q. hemisphaerica, Q. laurifolia, Q. myrtifolia, Q. palustris, Q. rubra, and Q. texana. [source]

Habit: Tree

Flowers: Bloom Period: February, March, April. • Flower Color: inconspicuous, none


Size: over 40' tall.


Mesic alluvial and lowland sites, also barrens , dunes, hammocks , and low ridges to steep slopes ; 0-450 m. Typically on mesic alluvial and lowland sites, Quercus nigra also occurs on a wide variety of soil types and in a diversity of habitats [3].

Typically found at an altitude of 0 to 1,092 meters (0 to 3,583 feet).[4]


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Duration: Perennial


Culture: Space 30-40' apart.

Soil: Minimum pH: 6.1 • Maximum pH: 7.5

Sunlight: Sun Exposure: Sun to Partial Shade.

Temperature: Cold Hardiness: 7a, 7b, 8a, 8b, 9a, 9b. (map)


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Q. nigra var. tridentifera Sargent • Q. uliginosa Wangenheim • Quercus agnostifolia K. Koch • Quercus aquatica (Lam.) Walter • Quercus aquatica var. attenuata Aiton • Quercus aquatica var. cuneata Aiton • Quercus aquatica var. dentata A. Dc. • Quercus aquatica var. elongata Aiton • Quercus aquatica var. hybrida Chapm. • Quercus aquatica var. indivisa Aiton • Quercus aquatica var. nana (Willd.) Nutt. • Quercus aquatica var. stipitata A. Dc. • Quercus bumeliifolia Riddell • Quercus dentata Bartram • Quercus ferruginea F.Michx. var. hybrida Dippel • Quercus genabii K. Koch • Quercus hemisphaerica var. nana (Willd.) Sarg. • Quercus ludoviciana var. microcarpa (Dippel) Rehder • Quercus marylandica Du Roi • Quercus microcarya Small • Quercus nana Willdenow • Quercus nigra f. microcarya (Small) Trel. • Quercus nigra f. plenocarpa Trel. • Quercus nigra f. saxicola Trel. • Quercus nigra var. aquatica Lam. • Quercus nigra var. heterophylla Aiton • Quercus nigra var. microcarya (Small) Trel. • Quercus nigra var. plenocarpa Trel. • Quercus nigra var. saxicola Trel. • Quercus nigra var. tridentata A. Dc. • Quercus nigra var. tridentifera Sarg. • Quercus noviorleani Petz. and G. Kirchn. • Quercus phellos var. microcarpa Dippel • Quercus quinqueloba Engelm. • Quercus uliginosa Wangenh.


Publishing author : Rugel ex A.DC. Publication : Prodr. (DC.) 16(2.1): 60 1864 [late Dec 1864]

Similar Species

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Members of the genus Quercus

ZipcodeZoo has pages for 413 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. breviloba (Shallow Lobed Oak) · 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. calliprinos (Quercus CalliprinosPalestine Oak) · Q. canariensis (Algerian Oak) · Q. capesii (Cape Oak) · Q. carmenensis (Mexican Oak) · Q. carpenteri (Quercus CarpenteriCarpenter S 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)

More Info

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Further Reading

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Data Sources

Accessed through GBIF Data Portal November 19, 2007:



  1. 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 [back]
  2. Kevin C. Nixon "Quercus". in Flora of North America Vol. 3. Oxford University Press. Online at [back]
  3. "Quercus nigra". in Flora of North America Vol. 3. Oxford University Press. Online at [back]
  4. Mean = 102.890 meters (337.566 feet), Standard Deviation = 129.800 based on 713 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 2015-01-30