Quercus fusiformis |
Quercus durata |
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escarpment live oak, live oak, plateau oak, Texas live oak |
leather oak |
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Habit | Trees, sometimes shrubs, subevergreen, trees to 25 m, shrubs often forming large clonal stands. | Shrubs, evergreen, 1-2(-3) m. Bark scaly. | ||||
Bark | dark brown or black, scaly. |
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Twigs | light gray, 1.5-3 mm diam., tomentulose, tomentulum often persistent in age. |
gray or yellowish, 1-3 mm diam., densely or sparsely tomentulose, often with prominent, yellowish, spreading hairs. |
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Buds | reddish or dark brown, subglobose or ovate, 1.5-3 mm; scale margins glabrous or puberulent. |
brown or reddish brown, ovoid or globose, 1-2 mm, glabrous or puberulent. |
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Leaves | blade oblong-elliptic to narrowly ovate or lanceolate, sometimes obovate, ± planar, (10-)35-90(-150) × (15-)20-40(-85) mm, base rounded to truncate or cordate, rarely cuneate, margins minutely revolute or flat, entire or irregularly 1-3 toothed on each side, teeth mucronate (rarely spinose in suckers or juveniles), secondary veins obscure, 8-10 on each side, apex obtuse-rounded or acute; surfaces abaxially whitish or glaucous, densely covered with minute, appressed, fused-stellate hairs, light green and glabrate in shade leaves, adaxially dark or light green, glossy, glabrous or with minute, scattered, stellate hairs. |
blade cupped or convex, rarely somewhat planar, (10-)15-40 × 7-15(-20) mm, base cuneate, rounded-attenuate, or truncate, margins entire or irregularly toothed, sometimes spinose, usually unevenly revolute, secondary veins 4-6 on each side, apex rounded or subacute; surfaces abaxially densely to sparsely covered with erect, stipitate, (1-)2-4(-6)-rayed hairs 1-4 mm, felty to touch, secondary veins prominent, adaxially grayish or yellowish, with dense or scattered, semi-erect or appressed hairs, secondary veins obscure or somewhat impressed. |
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Acorns | 1-3, on peduncle 3-30 mm; cup funnel-shaped, hemispheric, or deeply goblet-shaped, 8-15 mm deep × 6-12(-15) mm wide, base often constricted, scales whitish or grayish, thickened basally, keeled, acute-attenuate, tomentulose, tips reddish, glabrous or puberulent; nut dark brown, often with light brown longitudinal stripes, subfusiform and acute to narrowly barrel-shaped, rarely distally rounded, (17-)20-30(-33) × 8-15 mm, glabrous. |
solitary or paired, subsessile; cup reddish, hemispheric, deeply cup-shaped or turbinate, 4-6 mm deep × 12-18 mm wide, enclosing to 1/2 nut or more, scales reddish or yellowish, weakly to strongly tuberculate, often somewhat glandular; nut globose, ovoid or cylindric, 15-25 × 10-25 mm, apex rounded or obtuse, persistently minute-puberulent. |
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Cotyledons | connate. |
distinct. |
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Quercus fusiformis |
Quercus durata |
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Phenology | Flowering spring. | |||||
Habitat | Hills, grasslands, scrublands, open woodlands, oak-juniper woodland, and margins of thorn scrub, often on limestone or deep calcareous loams, sometimes on granular sand or gravel | |||||
Elevation | 0-1200 m (0-3900 ft) | |||||
Distribution |
OK; TX; Mexico (Coahuila, Nuevo León, and Tamaulipas)
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CA
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Discussion | The difficulty in distinguishing Texas populations of Quercus fusiformis from Q. virginiana is reflected in a variety of taxonomic treatments, including reducing Q. fusiformis to varietal rank under Q. virginiana. The latter disposition is problematic, however, because Q. fusiformis in northeastern Mexico is amply distinct from Q. virginiana and appears to be more closely related to Q. brandegei Goldmann, an endemic of Baja California, Mexico. Thus, here we assume that the intergradation of Q. virginiana and Q. fusiformis is a result of secondary contact, and is not primary clinal variation. Under this interpretation, Q. virginiana in typical form extends into Texas only as far west as the Brazos River drainage along the coast from there to the escarpment of the Edwards Plateau; most populations elsewhere are either intermediate between the two species or show greater affinity with Q. fusiformis. On the Edwards Plateau, the live oak populations are small trees forming rhizomatous copses (shinneries) and having mostly acute acorns. Populations of live oak on deep sands in south Texas differ from typical Quercus fusiformis in having broader, more rounded leaves, often with the secondary veins somewhat impressed abaxially, and relatively blunt, barrel-shaped acorns. These characteristics suggest introgresion from the Mexican-Central American species Q. oleoides Schlechtendal & Chamisso, which in its typical form reaches north only as far as southern Tamaulipas, Mexico. The name Q. oleoides var. quaterna C. H. Muller has been applied to what is apparently a shrub form of one of these Q. fusiformis × Q. oleoides hybrids. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Chaparral, oak woodlands, open pine forests, on serpentine and nonserpentine soils; 150-1500 m. Varieties 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 3. | FNA vol. 3. | ||||
Parent taxa | Fagaceae > Quercus > sect. Quercus | Fagaceae > Quercus > sect. Quercus | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Q. virginiana var. fusiformis | Q. dumosa var. bullata, Q. dumosa var. revoluta | ||||
Name authority | Small: Bull. Torrey Bot. Club 28: 357. (1901) | Jepson: Fl. Calif. 1(2): 356. (1909) | ||||
Web links |