Quercus arizonica |
Quercus emoryi |
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Arizona oak, Arizona white oak |
bellota, Emory oak, Emory's oak |
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Habit | Trees, evergreen or subevergreen, small to moderate-sized trees, rarely to 18 m. Bark scaly. | Trees or shrubs, evergreen, to 15 m. Bark dark brown to black, deeply fissured. |
Twigs | yellowish, 1.5-2.5 mm diam., persistently felty-tomentose, eventually dingy gray. |
dark reddish brown, 1-3 mm diam., pubescent. |
Buds | dull russet-brown, ovoid, distally subacute or rounded, 3 mm, sparsely pubescent or glabrate. |
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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 ovate to narrowly oblong to obovate, planar, 28-95 × 15-45 mm, base cordate, margins entire or spinose, with up to 13 awns, apex blunt to acute; surfaces abaxially glabrous except for tuft of tomentum on each side of midrib at base of blade, rarely completely glabrous, adaxially not rugous, glabrous or with a few hairs along midrib. |
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; cup cup-shaped, 5-7.5 mm high × 7-12 mm wide, covering 1/4-1/2 nut, outer surface pubescent to sparsely puberulent, inner surface pubescent to floccose, scale tips appressed, blunt; nut ellipsoid to oblong, 10-18 × 6-10 mm, glabrous to puberulent, especially at apex, scar diam. 3-5.5 mm. |
Cotyledons | connate. |
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Terminal | buds reddish brown, ovoid to subconic, 2.5-6.5 mm, glabrous except for tuft of hairs at apex, occasionally hairy on distal 1/2. |
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Quercus arizonica |
Quercus emoryi |
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Phenology | Flowering spring. | Flowering spring. |
Habitat | Oak and pinyon woodlands, margins of chaparral, arroyos | Foothills and slopes |
Elevation | 1300-2500(-3000) m (4300-8200(-9800) ft) | 1000-2200 m (3300-7200 ft) |
Distribution |
AZ; NM; TX; Mexico (Chihuahua, Coahuila, Durango, and Sonora)
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AZ; NM; TX; n Mexico
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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.) |
Quercus emoryi reportedly hybridizes with Q. graciliformis (= Q. ×tharpii C. H. Muller). (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. hastata |
Name authority | Sargent: Gard. & Forest 8: 92. (1895) | Torrey: in W. H. Emory, Not. Milit. Reconn., 151, plate 9. (1848) |
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