Quercus nigra |
Quercus carmenensis |
|
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chêne gris, water oak |
Mexican oak |
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Habit | Trees, deciduous or tardily deciduous, to 30 m. Bark grayish black, fissures irregular, shallow, inner bark pinkish. | Shrubs or trees, deciduous, shrubs 0.5-2 m, rhizomatous, trees (on better sites) to 12 m, trunk 0.75 m diam. |
Bark | light gray, checkered or furrowed. |
|
Twigs | dark red-brown, 1.5-2.5 mm diam., glabrous. |
often strikingly red, 1-1.5 mm diam., sparingly (rarely densely) stellate-pubescent, somewhat glabrescent and gray 2d year. |
Buds | light brown, nearly round, 1-1.5 mm, indumentum similar to twigs. |
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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 or narrowly obovate, (20-)30-50 × 10-30 mm, thin to moderately leathery, base cuneate to rounded, margins shallowly and irregularly lobed or coarsely toothed in distal 1/2, rarely subentire, teeth mucronate, secondary veins 9-12 on each side, branching or passing directly to teeth, apex acute, sometimes broadly rounded; surfaces abaxially light green or yellow-green, prominently pubescent with minute, erect velvety hairs, adaxially surfaces dark green, sparsely and minutely stellate-pubescent. |
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. |
solitary or paired, subsessile or short-pedunculate (immature); cup (mature) unknown; scales (immature) light brown, tip acute, canescent. |
Cotyledons | unknown. |
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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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Nut | unknown. |
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Quercus nigra |
Quercus carmenensis |
|
Phenology | Flowering spring. | |
Habitat | Mesic alluvial and lowland sites, also barrens, dunes, hammocks, and low ridges to steep slopes | Shrublands and woodlands on limestone |
Elevation | 0-450 m (0-1500 ft) | 2200-2500 m (7200-8200 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 (Coahuila) |
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.) |
Of conservation concern. Shrublands and woodlands on limestone; of conservation concern; 2200-2500 m; Tex.; Mexico (Coahuila). Quercus carmenensis is known in the United States from only one collection from the Chisos Mountains, Texas; otherwise, it is known in the Sierra del Carmen region, Coahuila, Mexico. (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 | |
Name authority | Linnaeus: Sp. Pl. 2: 995. (1753) | C. H. Muller: Amer. Midl. Naturalist 18: 847. (1937) |
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