Quercus arizonica |
Quercus hypoleucoides |
|
---|---|---|
Arizona oak, Arizona white oak |
silverleaf oak |
|
Habit | Trees, evergreen or subevergreen, small to moderate-sized trees, rarely to 18 m. Bark scaly. | Trees or shrubs, evergreen, to 10 m. Bark black, deeply furrowed. |
Twigs | yellowish, 1.5-2.5 mm diam., persistently felty-tomentose, eventually dingy gray. |
dark reddish brown, 1.5-3 mm diam., pubescent. |
Buds | dull russet-brown, ovoid, distally subacute or rounded, 3 mm, sparsely pubescent or glabrate. |
|
Leaves | blade elliptic or oblong to narrowly obovate or oblanceolate, planar or moderately convex, to (30-)40-80(-90) × 15-30 mm, thick and leathery, usually stiff, base cordate or rounded and weakly cordate, margins entire or coarsely toothed especially near apex, cartilaginously revolute, teeth mucronate-tipped, obscure or prominent, secondary veins ca. 7-11 on each side, branching, passing into teeth when present, apex acute to usually obtuse or broadly rounded; surfaces abaxially dull, sparsely pubescent or subtomentose with curly branched hairs, reticulate from prominent, raised secondary veins, usually glaucous where exposed, adaxially dark or bluish green, moderately lustrous, sparsely and minutely stellate-pubescent, secondary veins slightly raised or prominent within depressions or impressed. |
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. |
Acorns | solitary or paired, subsessile, occasionally on peduncle to 15 mm; cup hemispheric or cup-shaped, 5-10(-15) mm deep × 10-15 mm wide, enclosing ca. 1/2 nut, base rounded, margin rather coarse, scales cream to brown, broadly ovate, evenly and strongly tuberculate, tomentose, tips closely appressed; nut light brown, ovoid or oblong, 8-12 mm, nearly glabrous. |
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. |
Cotyledons | connate. |
|
Terminal | buds light chestnut brown, ovoid, 2.5-4.5 mm, glabrous except for ciliate scale margins, occasionally with tuft of hairs at apex. |
|
Quercus arizonica |
Quercus hypoleucoides |
|
Phenology | Flowering spring. | Flowering spring. |
Habitat | Oak and pinyon woodlands, margins of chaparral, arroyos | Common in moist canyons and on ridges |
Elevation | 1300-2500(-3000) m (4300-8200(-9800) ft) | 1500-2700 m (4900-8900 ft) |
Distribution |
AZ; NM; TX; Mexico (Chihuahua, Coahuila, Durango, and Sonora)
|
AZ; NM; TX; n Mexico
|
Discussion | Some of the specimens previously referred to Quercus endemica by C. H. Muller belong here instead. Putative hybrids between Quercus arizonica and Q. grisea (= Q. ×organensis Trelease) are problematic in local areas of contact from southeastern Arizona to western Texas. These intermediates tend to have narrower leaves than Q. arizonica, with moderately reticulate patterns of venation, and more densely hairy leaves. Quercus arizonica and Q. grisea are amply distinct elsewhere, including large areas in northern Mexico, and they appear to be more closely related to other species than to one another (e.g., Q. arizonica with Q. oblongifolia and Q. laeta Liebmann, and Q. grisea with Q. mohriana and Q. microphylla Née). Thus, Q. arizonica and Q. grisea are best treated as distinct species that hybridize, and not as conspecific populations. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 3. | FNA vol. 3. |
Parent taxa | Fagaceae > Quercus > sect. Quercus | Fagaceae > Quercus > sect. Lobatae |
Sibling taxa | ||
Synonyms | Q. sacame | Q. hypoleuca |
Name authority | Sargent: Gard. & Forest 8: 92. (1895) | A. Camus: Bull. Mus. Natl. Hist. Nat., sér. 2, 4: 124. (1932) |
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