Quercus fusiformis |
Quercus gravesii |
|
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escarpment live oak, live oak, plateau oak, Texas live oak |
Chisos red oak, Graves oak |
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Habit | Trees, sometimes shrubs, subevergreen, trees to 25 m, shrubs often forming large clonal stands. | Trees, deciduous, to 13 m. Bark black, roughly furrowed. |
Bark | dark brown or black, scaly. |
|
Twigs | light gray, 1.5-3 mm diam., tomentulose, tomentulum often persistent in age. |
light brown to dark reddish brown, (1-)1.5-2.5 mm diam., glabrous or glabrate. |
Buds | reddish or dark brown, subglobose or ovate, 1.5-3 mm; scale margins 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 ovate to elliptic, 45-140 × 20-120 mm, base rounded (rarely subcordate) to obtuse or cuneate, margins with 3-5 acute lobes, 9-20 awns, apex broadly obtuse or acute to attenuate, occasionally falcate; surfaces abaxially light green or coppery green, glabrous with small axillary tufts of tomentum or pubescent along midrib and veins, adaxially shiny or glossy, glabrous except for scattered pubescence near base and along midrib. |
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. |
biennial; cup turbinate or deeply cup-shaped, 4.5-8.5 mm high × 7.5-12 mm wide, covering 1/3-1/2 nut, outer surface glabrate, inner surface glabrous to pubescent on inner 2/3, scale tips appressed, less than 4 mm, acute; nut ovoid to ellipsoid, rarely subglobose or oblong, 9-16 × 5.5-11 mm, occasionally striate, glabrous to puberulent, especially at apex, scar diam. 3-6 mm. |
Cotyledons | connate. |
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Terminal | buds brown or reddish brown, ovoid or ellipsoid to subconic, 2-5 mm, glabrous or with tuft of hairs at apex. |
|
Quercus fusiformis |
Quercus gravesii |
|
Phenology | Flowering spring. | 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 | Davis, Glass, and Chisos mountains |
Elevation | 0-1200 m (0-3900 ft) | above 1200 m (above 3900 ft) |
Distribution |
OK; TX; Mexico (Coahuila, Nuevo León, and Tamaulipas)
|
TX; n Mexico |
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.) |
Quercus gravesii reportedly hybridizes with Q. hypoleucoides. As noted above, forms of Q. gravesii and Q. robusta are easily confused and give the impression of belonging to a single morphologic continuum. Some authors have also used the name Quercus texana for Q. gravesii. (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. virginiana var. fusiformis | Q. chisosensis, Q. shumardii var. microcarpa, Q. stellipila, Q. texana var. chisosensis, Q. texana var. stellapila |
Name authority | Small: Bull. Torrey Bot. Club 28: 357. (1901) | Sudworth: Check List For. Trees U.S., 86. (1927) |
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