Quercus fusiformis |
Quercus margarettae |
|
---|---|---|
escarpment live oak, live oak, plateau oak, Texas live oak |
dwarf post oak, runner oak, sand post oak |
|
Habit | Trees, sometimes shrubs, subevergreen, trees to 25 m, shrubs often forming large clonal stands. | |
Bark | dark brown or black, scaly. |
light gray, scaly. |
Twigs | light gray, 1.5-3 mm diam., tomentulose, tomentulum often persistent in age. |
green or reddish, becoming gray, 1-2(-3) mm diam., glabrous. |
Buds | reddish or dark brown, subglobose or ovate, 1.5-3 mm; scale margins glabrous or puberulent. |
reddish brown, ovoid, 2-3(-6) mm, apex obtuse, sparsely pubescent to glabrate. |
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 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 | 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. |
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 | connate. |
distinct. |
Small | trees or shrubs , deciduous, to 12 m, sometimes rhizomatous. |
|
Quercus fusiformis |
Quercus margarettae |
|
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 | Deep sands and gravels, often in dense woods as understory or in open scrubland and pine barrens |
Elevation | 0-1200 m (0-3900 ft) | 0-600 m (0-2000 ft) |
Distribution |
OK; TX; Mexico (Coahuila, Nuevo León, and Tamaulipas)
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AL; AR; FL; GA; LA; MO; MS; NC; OK; SC; TX; VA
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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.) |
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. virginiana var. fusiformis | Q. minor var. margaretta, Q. stellata var. margaretta |
Name authority | Small: Bull. Torrey Bot. Club 28: 357. (1901) | (Ashe) J. K. Small: in J. K. Small, Fl. S.E. U.S., 355. (1903) |
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