Quercus turbinella |
Quercus margarettae |
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grey oak, shrub live oak, Sonoran scrub oak, turbinella oak |
dwarf post oak, runner oak, sand post oak |
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Habit | Shrubs or small trees, evergreen or subevergreen, to 4 m. Bark light gray or brown, scaly. | |
Bark | light gray, scaly. |
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Twigs | brown to gray, 1-3 mm diam., usually tomentulose, sometimes glabrous, becoming glabrate. |
green or reddish, becoming gray, 1-2(-3) mm diam., glabrous. |
Buds | brown, round to ovoid, 1-2 mm, minutely pubescent. |
reddish brown, ovoid, 2-3(-6) mm, apex obtuse, sparsely pubescent to glabrate. |
Leaves | blade elliptic or ovate, (1.5-)20-30 × (5-)10-15(-20) mm, thick, leathery, base cordate or rounded, margins planar or slightly crisped-undulate, coarsely 3-5-toothed or very shallowly lobed on each side, teeth spinose with spines 1-1.5 mm, secondary veins 4-8 on each side, apex acute or obtuse; surfaces abaxially yellow or reddish, usually glaucous, minutely stellate-puberulent, adaxially grayish, glaucous, or yellowish glandular, glabrous or sparsely and minutely stellate-pubescent. |
blade obovate to narrowly obovate, (25-)40-80(-135) × 20-40(-80) mm, base cuneate to rounded-attenuate, margins moderately to deeply lobed, lobes rounded or spatulate, sometimes middle or distal 2 lobes compound, with secondary lobe on proximal side, divergent at right angles, forming cruciform pattern, secondary veins 3-5 on each side, apex broadly rounded; surfaces abaxially light green, with interlocking, erect, 2-4(-6)-rayed stellate hairs, velvety to touch, adaxially dark green, glossy, glabrous or sparsely stellate, not harsh to touch. |
Acorns | solitary or several, on axillary peduncle 10-40 mm; cup hemispheric or shallowly cup-shaped, 4-6 mm deep × 8-12 mm wide, covering 1/4-1/2 nut, scales tightly appressed, ovate, moderately tuberculate, grayish or yellowish puberulent; nut light brown, ovoid, to 20 × 11 mm, minutely puberulent or glabrate. |
1-3, subsessile or on peduncle to 20 mm; cup deeply cup-shaped, basally rounded or constricted, (7-)9-12 mm deep × 12-20 mm wide, enclosing to 3/4 nut, scales loosely appressed, finely grayish pubescent; nut light brown, ovoid, 15-25(-30) × 9-13(-16) mm, glabrous. |
Cotyledons | distinct. |
distinct. |
Small | trees or shrubs , deciduous, to 12 m, sometimes rhizomatous. |
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Quercus turbinella |
Quercus margarettae |
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Phenology | Flowering spring. | |
Habitat | Dry desert slopes, often in juniper and pinyon woodlands | Deep sands and gravels, often in dense woods as understory or in open scrubland and pine barrens |
Elevation | 800-2000 m (2600-6600 ft) | 0-600 m (0-2000 ft) |
Distribution |
AZ; CA; CO; NM; NV; TX; UT; Mexico (Baja California, Sonora, and probably n Chihuahua)
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AL; AR; FL; GA; LA; MO; MS; NC; OK; SC; TX; VA
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Discussion | Formerly, California populations of what here is referred to as Quercus john-tuckeri have been included in the concept of Q. turbinella. Quercus john-tuckeri has subsessile fruit and noncordate leaf bases as opposed to the consistently pedunculate fruit and strongly cordate leaf bases of Q. turbinella. The two species seem to be no more closely related to each other than each might be to other southwestern oaks, and Q. john-tuckeri shares at least as many characteristics with Q. berberidifolia as with Q. turbinella. Thus, treatment of these two taxa as varieties of the same species is inappropriate. Quercus turbinella forms putative hybrid swarms with Q. gambelii (see treatment), as well as with Q. grisea. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Historical records for Quercus margaretta exist for New York, but no current population is known there. Populations of post oak in east Texas (the Cross Timbers region) on sands and gravels exhibit characteristics somewhat intermediate between Quercus stellata and Q. margaretta; most of the trees at those localities have leaves with abaxial surface similar to Q. margaretta, leaf shape more similar to Q. stellata, and twigs somewhat intermediate between the two species in diameter and varying from tightly pubescent to glabrate. Acorn characters tend toward Q. margaretta as well. These populations have been treated as Q. drummondii Liebmann, the Drummond post oak. Similar intermediates occur sporadically throughout the range of the post oaks in southeastern United States, but they do not form such continuous and morphologically stable populations; perhaps the Texas material is best treated as a nothospecies, Q. ×drummondii. (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. dumosa var. turbinella, Q. subturbinella | Q. minor var. margaretta, Q. stellata var. margaretta |
Name authority | Greene: Ill. W. Amer. Oaks 1: 37. (1889) | (Ashe) J. K. Small: in J. K. Small, Fl. S.E. U.S., 355. (1903) |
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