Quercus incana |
Quercus oblongifolia |
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bluejack oak |
Mexican blue oak, Sonoran blue oak |
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Habit | Trees, deciduous, to 10 m. Bark dark brown to black with square plates. | Trees, evergreen, to 10 m. Bark gray or whitish, closely furrowed. |
Twigs | brown to reddish brown, 1-2.5 mm diam., tomentose to sparsely pubescent. |
light brown, 1-1.5 mm diam., densely or sparsely stellate-tomentose, soon glabrate. |
Buds | reddish brown, subspheric to broadly ovoid, 1-2 mm, glabrous or basal scales pubescent; stipules persistent about terminal buds. |
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Leaves | blade narrowly ovate or elliptic to obovate, usually widest near middle, planar, 30-100 × 12-35 mm, base acute (rarely attenuate) to rounded, margins entire, with 1 apical awn (leaves on juvenile or 2d-flush growth may have 2-3 shallow lobes and 3-5 awns), apex acute or obtuse, rarely rounded; surfaces abaxially densely tomentose, hairs in vein axils often reddish, easily distinguished from others, adaxially often glossy, sparsely pubescent, especially along midrib and near base, veins often raised. |
blade oblong to elliptic, occasionally lanceolate or ovate, (20-)30-60(-80) × (5-)10-25(-30) mm, base cuneate to cordate, margins entire, undulate, sometimes irregularly toothed especially toward apex, secondary veins 7-8(-10) on each side, branched, apex acute or broadly rounded; surfaces abaxially densely and loosely glandular-tomentose, quickly glabrate or persistently floccose, especially about base of midrib, at maturity strongly glaucous, adaxially dull pale green, bluish green, or glaucous, sparsely stellate-tomentose, quickly glabrate. |
Acorns | biennial; cup saucer-shaped to bowl-shaped, 4.5-8 mm high × 10-18 mm wide, covering 1/4-1/3(-1/2) nut, outer surface pubescent or puberulent, inner surface uniformly pubescent, scale tips tightly appressed, obtuse or acute; nut ovoid (rarely subglobose) to broadly ellipsoid, 10-17 × 10-16 mm, occasionally striate, glabrate, scar diam. 5.5-10.5 mm. |
solitary or paired, subsessile or on peduncle 4-12 mm; cup cup-shaped, about 6-8(-13) mm deep × 10-13 mm wide, enclosing ca. 1/3 nut, scales to 1-1.5 mm wide, moderately, regularly tuberculate near base of cup, gray-pubescent; nut light brown, ovoid or oblong, 12-17(-19) × (7-)10-12 mm, glabrate or puberulent about apex. |
Cotyledons | connate. |
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Terminal | buds light brown to reddish brown, narrowly ovoid to conic, 3.5-7 mm, distinctly 5-angled in cross section, scales pubescent, often tuft of reddish or silvery hairs at apex. |
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Quercus incana |
Quercus oblongifolia |
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Phenology | Flowering spring. | Flowering in spring. |
Habitat | Well-drained sandy soils of barrens, hammocks, dunes, and upland ridges | Common in high grasslands and midelevation woodlands, mesas, and canyons |
Elevation | 0-250 m (0-800 ft) | 1300-1650 m (4300-5400 ft) |
Distribution |
AL; AR; FL; GA; LA; MS; NC; OK; SC; TX; VA
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AZ; NM; TX; Mexico (Baja California South, Sonora, Chihuahua, and Coahuila)
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Discussion | Quercus incana reportedly hybridizes with Q. falcata [= Q. ×subintegra (Engelmann) Trelease], Q. hemisphaerica (D. M. Hunt 1989), Q. laurifolia (= Q. ×atlantica Ashe), Q. laevis (= Q. ×asheana Little), Q. marilandica (= Q. ×cravenensis Little), Q. nigra (= Q. ×caduca Trelease), and Q. phellos (E. J. Palmer 1948); with Q. pumila (D. M. Hunt 1989); and with Q. velutina (= Q. ×podophylla Trelease), and questionably, Q. myrtifolia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 3. | FNA vol. 3. |
Parent taxa | Fagaceae > Quercus > sect. Lobatae | Fagaceae > Quercus > sect. Quercus |
Sibling taxa | ||
Synonyms | Q. cinerea | |
Name authority | W. Bartram: Travels Carolina, 378. (1791) | Torrey: in L. Sitgreaves, Rep. Exped. Zuni Colorado Rivers, 173, plate 19. (1853) |
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