Quercus nigra |
Quercus depressipes |
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chêne gris, water oak |
Davis Mountain oak, depressed oak |
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Habit | Trees, deciduous or tardily deciduous, to 30 m. Bark grayish black, fissures irregular, shallow, inner bark pinkish. | Shrubs, evergreen or subevergreen, low, to 1 m, often forming dense thickets, rhizomatous. |
Bark | gray, scaly. |
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Twigs | dark red-brown, 1.5-2.5 mm diam., glabrous. |
tan-brown, becoming reddish gray, 1-1.5 mm diam., glabrate or hairy. |
Buds | tan or brown, subglobose, 1-1.5 mm, glabrate or scales inconspicuously ciliate. |
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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 oblong to elliptic, 10-25(-60) × 8-25 mm, thick, leathery, base moderately to deeply cordate, petiole strongly depressed in basal sinus, margins inconspicuously toothed in distal 1/2, rarely entire, sometimes sublobate, somewhat revolute, secondary veins 5 or 6 on each side with few intermediates, branching, apex broadly rounded to subacute; surfaces abaxially dull gray-green or glaucous, completely glabrous or with a few stellate hairs on midrib, adaxially similar to abaxial surface, secondary veins somewhat raised on both surfaces. |
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. |
paired on peduncle 7-15 mm; cup 4-7 mm deep × 8-13 mm wide, goblet-shaped, enclosing 1/4-1/2 nut, base somewhat constricted or rounded, scales moderately tuberculate, proximally densely gray-tomentose, tips rather closely appressed, reddish brown, abaxially glabrous, ciliate; nut tan-brown, elliptic to ovoid or globose, to 10-15 × 10-11 mm, apex rounded, glabrous. |
Cotyledons | connate. |
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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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Quercus nigra |
Quercus depressipes |
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Phenology | Flowering spring. | Flowering spring. |
Habitat | Mesic alluvial and lowland sites, also barrens, dunes, hammocks, and low ridges to steep slopes | Grassland and open wooded slopes |
Elevation | 0-450 m (0-1500 ft) | 2100-2600 m (6900-8500 ft) |
Distribution |
AL; AR; DE; FL; GA; KY; LA; MD; MO; MS; NC; NJ; OK; SC; TN; TX; VA
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TX; Mexico (Chihuahua, Durango, and Zacatecas) |
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.) |
Quercus depressipes enters the United States in only one population on the highest portion of Mt. Livermore in trans-Pecos Texas; it has a wider distribution in the dry altiplano of northern Mexico. Its most distinctive characteristics are the combination of dwarf clonal habit, small glaucous leaves without spinose teeth, and connate cotyledons. In northern Mexico, it hybridizes locally with Q. rugosa. (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. bocoynensis |
Name authority | Linnaeus: Sp. Pl. 2: 995. (1753) | Trelease: Mem. Natl. Acad. Sci. 20: 90. (1924) |
Web links |