Quercus arizonica |
Quercus boyntonii |
|
---|---|---|
Arizona oak, Arizona white oak |
Boynton oak, Boynton sand post oak, Boynton's oak, Boynton's sand post oak |
|
Habit | Trees, evergreen or subevergreen, small to moderate-sized trees, rarely to 18 m. Bark scaly. | Shrubs, rarely small trees, deciduous or subevergreen, shrubs low, under 2 m, often trailing, rhizomatous, trees to 6 m. Bark brown, scaly. |
Twigs | yellowish, 1.5-2.5 mm diam., persistently felty-tomentose, eventually dingy gray. |
light brown, 1.5-3 mm diam., densely tomentulose. |
Buds | dull russet-brown, ovoid, distally subacute or rounded, 3 mm, sparsely pubescent or glabrate. |
reddish brown, ovoid, 2-3(-4) mm, apex acute or rounded, sparsely pubescent. |
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 obovate or oblanceolate, (39-)50-100(-125) × 20-60(-91) mm, base cuneate, margins minutely revolute, broadly 3-lobed distally or with 3-5 rounded, irregular lobes in distal 1/2, secondary veins curved, 6-8 on each side, apex broadly ovate or triangular-lobed; surfaces abaxially grayish or silvery, densely tomentulose-glandular with minute, appressed-stellate hairs, adaxially dark green, glossy, glabrous or with minute, scattered, simple hairs. |
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. |
1-2, on peduncle 2-10(-35) mm; cup deeply or shallowly cup-shaped, 5-10 mm deep × 10-13 mm wide, including 1/3-1/2 nut, scales closely appressed, gray, tomentulose; nut light brown, ovoid, 10-17 × 7-13 mm, apex rounded, glabrous. |
Cotyledons | connate. |
distinct. |
Quercus arizonica |
Quercus boyntonii |
|
Phenology | Flowering spring. | Flowering spring. |
Habitat | Oak and pinyon woodlands, margins of chaparral, arroyos | Deep sands and crevices in pine forests, along streams |
Elevation | 1300-2500(-3000) m (4300-8200(-9800) ft) | 0-200 m (0-700 ft) |
Distribution |
AZ; NM; TX; Mexico (Chihuahua, Coahuila, Durango, and Sonora)
|
AL; TX
|
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.) |
Of conservation concern. Quercus boyntonii is a rare and poorly known species of somewhat uncertain distribution; probably it is often overlooked. Some intermediates between Q. boyntonii and Q. margaretta are known. These tend to be larger shrubs, to 2 m with felty hairs proximally but with the rhizomatous habit of Q. boyntonii. (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. stellata var. boyntonii |
Name authority | Sargent: Gard. & Forest 8: 92. (1895) | Beadle: Biltmore Bot. Stud. 1: 47. (1901) |
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