Quercus hypoleucoides |
Quercus sinuata |
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silverleaf oak |
bastard oak, bastard white oak, Durand oak, Durand white oak |
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Habit | Trees or shrubs, evergreen, to 10 m. Bark black, deeply furrowed. | Trees or shrubs, deciduous, to 15(-20) m, with solitary or multiple trunks. | ||||
Bark | gray to light brown, flaky to papery and exfoliating. |
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Twigs | dark reddish brown, 1.5-3 mm diam., pubescent. |
light gray or gray, 1-2(-3) mm diam., glabrous, rarely minutely puberulent. |
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Buds | brown or reddish brown, broadly ovoid, 2-3 mm, essentially glabrous. |
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Leaves | blade narrowly ovate to ovate or elliptic, 45-120 × 15-40 mm, base cuneate to rounded, margins strongly revolute, entire or spinose with up to 11 awns, apex acute to attenuate; surfaces abaxially densely tawny- or white-tomentose, adaxially noticeably rugose, glabrous. |
blade oblong to oblanceolate, or narrowly rhomboid, or cuneiform, or rounded-3-dentate, (25-)30-120(-140) × (15-)25-60 mm, base acute, cuneate, attenuate-rounded, or obtuse, margins entire to irregularly toothed or moderately, sinuately lobed, flat, secondary veins ca. 7-11 on each side, apex broadly rounded, rarely attenuately narrowed or obscurely 3-lobed; surfaces abaxially silvery or dull green, with scattered to crowded, minute, appressed-stellate, 8-10-rayed hairs, or glabrate or glabrous, especially in shade forms, adaxially green or dull green, glabrous. |
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Acorns | annual or biennial; cup deeply saucer- or cup-shaped, 4.5-7 mm high × 6-13 mm wide, covering 1/3 nut or less, outer surface pubescent to sparsely puberulent, inner surface pubescent to floccose, scales appressed, blunt; nut ellipsoid to oblong, 8-16 × 5-10 mm, glabrous, scar diam. 2.5-5.5 mm. |
solitary or paired, subsessile or on axillary peduncle to 1-7 mm; cup saucer-shaped to shallowly cup-shaped, rarely deeper, 2-8 mm deep × 8-15(-20) mm wide, enclosing 1/8-1/4 nut, rarely more, base flat, rounded, or constricted, margin thin, scales closely appressed, grayish with reddish margins, ovate, flat, obtuse, not tuberculate; nut light brown, depressed-ovoid to oblong, 7-15 × 7-12(-17) mm, glabrous. |
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Cotyledons | distinct. |
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Terminal | buds light chestnut brown, ovoid, 2.5-4.5 mm, glabrous except for ciliate scale margins, occasionally with tuft of hairs at apex. |
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Quercus hypoleucoides |
Quercus sinuata |
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Phenology | Flowering spring. | |||||
Habitat | Common in moist canyons and on ridges | |||||
Elevation | 1500-2700 m (4900-8900 ft) | |||||
Distribution |
AZ; NM; TX; n Mexico
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AL; AR; FL; GA; LA; MS; NC; OK; SC; TX
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Discussion | Quercus hypoleucoides reportedly hybridizes with Q. gravesii (Q. ×inconstans E. J. Palmer [= Q. livermorensis C. H. Muller]) (see C. H. Muller 1951). Several specimens from Pima County, Arizona, fall outside the range of typical Q. hypoleucoides, suggesting hybridization with the Mexican Q. mcvaughii Spellenberg (R. Spellenberg 1992). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Varieties 2 (2 in the flora). The question of the correct name for this species has persisted, with some authors rejecting the usage here in favor of Quercus durandii. Although no type material is extant, the original description of Q. sinuata is consistent with the concept presented here, as by W. W. Ashe (1916) and W. Trelease (1924), and inconsistent with any other oak from the broad area covered by Thomas Walter's Flora Caroliniana (1788). The two varieties differ in habit, habitat, leaf size and lobing, and geographic range, and considerable variability exists within both varities as to the degree and density of silvery stellate-pubescence on the abaxial surface of the leaf. Sun leaves of both tend to have a higher proportion of silvery pubescence, and shade leaves and some individual trees tend to have more glabrate leaves, although evidence of flat-stellate trichomes is usually apparent. Plants with young, expanding leaves sometimes are mistaken for Quercus nigra, a member of the red oak group. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 3. | FNA vol. 3. | ||||
Parent taxa | Fagaceae > Quercus > sect. Lobatae | Fagaceae > Quercus > sect. Quercus | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Q. hypoleuca | Q. durandii | ||||
Name authority | A. Camus: Bull. Mus. Natl. Hist. Nat., sér. 2, 4: 124. (1932) | Walter: Fl. Carol., 235. (1788) | ||||
Web links |