Quercus palmeri |
Quercus depressipes |
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Palmer oak, Palmer's oak |
Davis Mountain oak, depressed oak |
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Habit | Shrubs, evergreen or subevergreen, low, to 1 m, often forming dense thickets, rhizomatous. | |
Bark | gray, scaly. |
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Twigs | tan-brown, becoming reddish gray, 1-1.5 mm diam., glabrate or hairy. |
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Buds | tan or brown, subglobose, 1-1.5 mm, glabrate or scales inconspicuously ciliate. |
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Leaves | blade suborbiculate, elliptic to round-ovate, 20-30(-50) × 20-40 mm, crisped, leathery and brittle, base obtuse to strongly subcordate, secondary veins 5-8(-12) pairs, each terminating in spine, basal pairs recurving, others branching at 45° angles, raised abaxially, margins spinose-dentate to occasionally entire, with highly thickened cell walls, spines cartilaginous, (1-)1.5-2 mm, apex broadly rounded or subacute, spinose; surfaces abaxially glaucous with waxy layer, often obscured by golden brown glandular hairs, adaxially grayish dark green, scurfy with fasciculate erect and twisting hairs. |
blade oblong to elliptic, 10-25(-60) × 8-25 mm, thick, leathery, base moderately to deeply cordate, petiole strongly depressed in basal sinus, margins inconspicuously toothed in distal 1/2, rarely entire, sometimes sublobate, somewhat revolute, secondary veins 5 or 6 on each side with few intermediates, branching, apex broadly rounded to subacute; surfaces abaxially dull gray-green or glaucous, completely glabrous or with a few stellate hairs on midrib, adaxially similar to abaxial surface, secondary veins somewhat raised on both surfaces. |
Acorns | solitary or rarely paired; cup turbinate to saucer-shaped, margins involute, often irregular, 7-10 mm deep × 10-25(-35) mm wide, scales appressed, embedded, often appearing laterally connate into concentric rings with only tip of scale visible, tuberculate, densely golden-tomentose throughout; nut oblong to fusiform, 20-30 × 10-15 mm, apex acute. |
paired on peduncle 7-15 mm; cup 4-7 mm deep × 8-13 mm wide, goblet-shaped, enclosing 1/4-1/2 nut, base somewhat constricted or rounded, scales moderately tuberculate, proximally densely gray-tomentose, tips rather closely appressed, reddish brown, abaxially glabrous, ciliate; nut tan-brown, elliptic to ovoid or globose, to 10-15 × 10-11 mm, apex rounded, glabrous. |
Cotyledons | connate. |
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Small | trees and shrubs, to 2-3 m. Twigs rigid, divaricately branched at 65-90° angles, reddish brown, 1.5-3 mm diam., pubescent, sparsely so in 2d year. |
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Terminal | buds ovoid, 1-1.5 mm, apex rounded, glabrous. |
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Quercus palmeri |
Quercus depressipes |
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Phenology | Flowering in spring. | Flowering spring. |
Habitat | Disjunct in canyons, mountain washes, dry thickets, and margins of chapparal communities | Grassland and open wooded slopes |
Elevation | 700-1800 m (2300-5900 ft) | 2100-2600 m (6900-8500 ft) |
Distribution |
AZ; CA; Mexico (n Baja California)
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TX; Mexico (Chihuahua, Durango, and Zacatecas) |
Discussion | Populations of Quercus palmeri are often small and may exist as single clones. The disjunct populations of California and Baja California are consistent morphologically. In Arizona populations, individuals tend to have flatter leaves bearing fewer teeth; this distinction is not constant, however. Morphologically aberrant populations identified as Q. palmeri in eastern Arizona (Chiracahua, Huachuca, and Santa Catalina mountains) and southwestern New Mexico are most likely the result of introgression from Q. palmeri to Q. chrysolepis (J. M. Tucker and H. S. Haskell 1960). Those populations tend to be intermediate in overall morphology, but all lack the diagnostic trichomes and biochemical markers of Q. palmeri; they are best classified as Q. chrysolepis affinity Q. palmeri. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Quercus depressipes enters the United States in only one population on the highest portion of Mt. Livermore in trans-Pecos Texas; it has a wider distribution in the dry altiplano of northern Mexico. Its most distinctive characteristics are the combination of dwarf clonal habit, small glaucous leaves without spinose teeth, and connate cotyledons. In northern Mexico, it hybridizes locally with Q. rugosa. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 3. | FNA vol. 3. |
Parent taxa | Fagaceae > Quercus > sect. Protobalanus | Fagaceae > Quercus > sect. Quercus |
Sibling taxa | ||
Synonyms | Q. dunnii | Q. bocoynensis |
Name authority | Engelmann: in S. Watson, Bot. California 2: 97. (1880) | Trelease: Mem. Natl. Acad. Sci. 20: 90. (1924) |
Web links |