Quercus nigra |
Quercus margarettae |
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chêne gris, water oak |
dwarf post oak, runner oak, sand post oak |
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Habit | Trees, deciduous or tardily deciduous, to 30 m. Bark grayish black, fissures irregular, shallow, inner bark pinkish. | |
Bark | light gray, scaly. |
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Twigs | dark red-brown, 1.5-2.5 mm diam., glabrous. |
green or reddish, becoming gray, 1-2(-3) mm diam., glabrous. |
Buds | reddish brown, ovoid, 2-3(-6) mm, apex obtuse, sparsely pubescent to glabrate. |
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Leaves | 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. |
blade obovate to narrowly obovate, (25-)40-80(-135) × 20-40(-80) mm, base cuneate to rounded-attenuate, margins moderately to deeply lobed, lobes rounded or spatulate, sometimes middle or distal 2 lobes compound, with secondary lobe on proximal side, divergent at right angles, forming cruciform pattern, secondary veins 3-5 on each side, apex broadly rounded; surfaces abaxially light green, with interlocking, erect, 2-4(-6)-rayed stellate hairs, velvety to touch, adaxially dark green, glossy, glabrous or sparsely stellate, not harsh to touch. |
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. |
1-3, subsessile or on peduncle to 20 mm; cup deeply cup-shaped, basally rounded or constricted, (7-)9-12 mm deep × 12-20 mm wide, enclosing to 3/4 nut, scales loosely appressed, finely grayish pubescent; nut light brown, ovoid, 15-25(-30) × 9-13(-16) mm, glabrous. |
Cotyledons | distinct. |
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Terminal | buds reddish brown, ovoid, 3-6.5 mm, puberulent throughout, occasionally densely pubescent on apical 2/3. |
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Small | trees or shrubs , deciduous, to 12 m, sometimes rhizomatous. |
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Quercus nigra |
Quercus margarettae |
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Phenology | Flowering spring. | |
Habitat | Mesic alluvial and lowland sites, also barrens, dunes, hammocks, and low ridges to steep slopes | Deep sands and gravels, often in dense woods as understory or in open scrubland and pine barrens |
Elevation | 0-450 m (0-1500 ft) | 0-600 m (0-2000 ft) |
Distribution |
AL; AR; DE; FL; GA; KY; LA; MD; MO; MS; NC; NJ; OK; SC; TN; TX; VA
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AL; AR; FL; GA; LA; MO; MS; NC; OK; SC; TX; VA
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Discussion | Typically on mesic alluvial and lowland sites, Quercus nigra also occurs on a wide variety of soil types and in a diversity of habitats. Trees with 3-lobed leaves with attenuate bases have been recognized as Quercus nigra var. tridentifera Sargent. 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. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Historical records for Quercus margaretta exist for New York, but no current population is known there. Populations of post oak in east Texas (the Cross Timbers region) on sands and gravels exhibit characteristics somewhat intermediate between Quercus stellata and Q. margaretta; most of the trees at those localities have leaves with abaxial surface similar to Q. margaretta, leaf shape more similar to Q. stellata, and twigs somewhat intermediate between the two species in diameter and varying from tightly pubescent to glabrate. Acorn characters tend toward Q. margaretta as well. These populations have been treated as Q. drummondii Liebmann, the Drummond post oak. Similar intermediates occur sporadically throughout the range of the post oaks in southeastern United States, but they do not form such continuous and morphologically stable populations; perhaps the Texas material is best treated as a nothospecies, Q. ×drummondii. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 3. | FNA vol. 3. |
Parent taxa | Fagaceae > Quercus > sect. Lobatae | Fagaceae > Quercus > sect. Quercus |
Sibling taxa | ||
Synonyms | Q. nana, Q. nigra var. tridentifera, Q. uliginosa | Q. minor var. margaretta, Q. stellata var. margaretta |
Name authority | Linnaeus: Sp. Pl. 2: 995. (1753) | (Ashe) J. K. Small: in J. K. Small, Fl. S.E. U.S., 355. (1903) |
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