Quercus arizonica |
Quercus john-tuckeri |
|
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Arizona oak, Arizona white oak |
desert scrub oak, Tucker oak, Tucker's oak |
|
Habit | Trees, evergreen or subevergreen, small to moderate-sized trees, rarely to 18 m. Bark scaly. | Shrubs, subevergreen or evergreen, 1-3(-5) m. Bark light gray or brown, scaly. |
Twigs | yellowish, 1.5-2.5 mm diam., persistently felty-tomentose, eventually dingy gray. |
yellowish or dingy gray, 1-1.5(-2) mm diam., densely tomentulose. |
Buds | dull russet-brown, ovoid, distally subacute or rounded, 3 mm, sparsely pubescent or glabrate. |
brown, ovoid or globose, 1.5-2(-3) mm, glabrous except for ciliate margins of scales; proximal scales often yellowish puberulent. |
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 unicolored, elliptic or obovate, (10-)15-30(-40) × (8-)10-15(-20) mm, thick and leathery, often brittle, base truncate or rounded-attenuate, rarely subcordate, margins irregularly spinose-toothed, occasionally shallowly lobate, secondary veins (3-)4-7, often some veins branching near margin and passing into more than 1 tooth, apex acute or rounded; surfaces abaxially waxy grayish, light green, or yellowish, sparse to moderately dense (8-)10-12-rayed, (loosely) appressed-stellate hairs, often 0.2-0.5 mm diam., and sparse to crowded, yellowish, glandular hairs, adaxially dull grayish, with stellate hairs, similar to abaxial surface. |
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. |
solitary or paired, subsessile; cup cup-shaped or obconic to hemispheric, 5-7 mm deep × 10-15 mm wide, thin, scales whitish or yellowish, moderately or scarcely tuberculate, puberulent; nut fusiform, ovoid, or conic, 20-30 mm, apex acute. |
Cotyledons | connate. |
distinct. |
Quercus arizonica |
Quercus john-tuckeri |
|
Phenology | Flowering spring. | |
Habitat | Oak and pinyon woodlands, margins of chaparral, arroyos | Dry slopes, chaparral, pinyon and juniper woodlands, margins of oak woodlands and sagebrush |
Elevation | 1300-2500(-3000) m (4300-8200(-9800) ft) | 900-2000 m (3000-6600 ft) |
Distribution |
AZ; NM; TX; Mexico (Chihuahua, Coahuila, Durango, and Sonora)
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CA
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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.) |
Dry slopes, chaparral, pinyon and juniper woodlands, margins of oak woodlands and sagebrush; 900-2000 m; Calif. Endemic to California, Quercus john-tuckeri occurs from Los Angeles County northward in the interior Coast Ranges and Sierra Foothills to the northern edge of Sacramento Valley. Quercus john-tuckeri bears some resemblance to both Q. turbinella and Q. berberidifolia. Quercus turbinella has pedunculate fruit and cordate leaf bases, however, and Q. berberidifolia has a glabrate adaxial leaf surface, substantially smaller stellate trichomes with fewer rays on the abaxial leaf surface, heavier tuberculate acorn cups, and blunt or rounded (instead of acute) acorns. (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. Quercus |
Sibling taxa | ||
Synonyms | Q. sacame | Q. turbinella subsp. californica |
Name authority | Sargent: Gard. & Forest 8: 92. (1895) | Nixon & C. H. Muller: Novon 4: 391. (1994) |
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