Quercus john-tuckeri |
Quercus fusiformis |
|
---|---|---|
desert scrub oak, Tucker oak, Tucker's oak |
escarpment live oak, live oak, plateau oak, Texas live oak |
|
Habit | Shrubs, subevergreen or evergreen, 1-3(-5) m. Bark light gray or brown, scaly. | Trees, sometimes shrubs, subevergreen, trees to 25 m, shrubs often forming large clonal stands. |
Bark | dark brown or black, scaly. |
|
Twigs | yellowish or dingy gray, 1-1.5(-2) mm diam., densely tomentulose. |
light gray, 1.5-3 mm diam., tomentulose, tomentulum often persistent in age. |
Buds | brown, ovoid or globose, 1.5-2(-3) mm, glabrous except for ciliate margins of scales; proximal scales often yellowish puberulent. |
reddish or dark brown, subglobose or ovate, 1.5-3 mm; scale margins glabrous or puberulent. |
Leaves | blade unicolored, elliptic or obovate, (10-)15-30(-40) × (8-)10-15(-20) mm, thick and leathery, often brittle, base truncate or rounded-attenuate, rarely subcordate, margins irregularly spinose-toothed, occasionally shallowly lobate, secondary veins (3-)4-7, often some veins branching near margin and passing into more than 1 tooth, apex acute or rounded; surfaces abaxially waxy grayish, light green, or yellowish, sparse to moderately dense (8-)10-12-rayed, (loosely) appressed-stellate hairs, often 0.2-0.5 mm diam., and sparse to crowded, yellowish, glandular hairs, adaxially dull grayish, with stellate hairs, similar to abaxial surface. |
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. |
Acorns | solitary or paired, subsessile; cup cup-shaped or obconic to hemispheric, 5-7 mm deep × 10-15 mm wide, thin, scales whitish or yellowish, moderately or scarcely tuberculate, puberulent; nut fusiform, ovoid, or conic, 20-30 mm, apex acute. |
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. |
Cotyledons | distinct. |
connate. |
Quercus john-tuckeri |
Quercus fusiformis |
|
Phenology | Flowering spring. | |
Habitat | Dry slopes, chaparral, pinyon and juniper woodlands, margins of oak woodlands and sagebrush | 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 | 900-2000 m (3000-6600 ft) | 0-1200 m (0-3900 ft) |
Distribution |
CA
|
OK; TX; Mexico (Coahuila, Nuevo León, and Tamaulipas)
|
Discussion | Dry slopes, chaparral, pinyon and juniper woodlands, margins of oak woodlands and sagebrush; 900-2000 m; Calif. Endemic to California, Quercus john-tuckeri occurs from Los Angeles County northward in the interior Coast Ranges and Sierra Foothills to the northern edge of Sacramento Valley. Quercus john-tuckeri bears some resemblance to both Q. turbinella and Q. berberidifolia. Quercus turbinella has pedunculate fruit and cordate leaf bases, however, and Q. berberidifolia has a glabrate adaxial leaf surface, substantially smaller stellate trichomes with fewer rays on the abaxial leaf surface, heavier tuberculate acorn cups, and blunt or rounded (instead of acute) acorns. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 3. | FNA vol. 3. |
Parent taxa | Fagaceae > Quercus > sect. Quercus | Fagaceae > Quercus > sect. Quercus |
Sibling taxa | ||
Synonyms | Q. turbinella subsp. californica | Q. virginiana var. fusiformis |
Name authority | Nixon & C. H. Muller: Novon 4: 391. (1994) | Small: Bull. Torrey Bot. Club 28: 357. (1901) |
Web links |