Quercus cornelius-mulleri |
Quercus mohriana |
|
---|---|---|
desert scrub oak, muller oak, muller's oak |
Mohr oak, Mohr's oak, Mohr's shinoak |
|
Habit | Shrubs, evergreen or subevergreen, densely branched, 1-2(-3) m. Bark gray, scaly. | Shrubs or trees, evergreen or deciduous, shrubs erect, rhizomatous, trees small, 0.5-3 m. Bark pale, rough and deeply furrowed. |
Twigs | gray, yellowish, or brownish, 1-1.5 mm diam., densely tomentulose, rarely glabrate. |
yellowish or whitish, 1-2 mm diam., felty-tomentose. |
Buds | dull brown, ovoid, 2.5-3 mm, glabrous except for margins of scales. |
dark red-brown, round-ovoid, 2 mm, glabrous, occasionally puberulent on outer scales, not subtended by persistent, hairy, subulate stipules. |
Leaves | blade strongly bicolored, ovate to oblong or narrowly obovate, 15-35 ×10-20 mm, rather thick and leathery, base cuneate or attenuate-rounded, margins entire or irregularly, shallowly toothed, teeth mucronate, rarely spinose, secondary veins 6-7 on each side, apex rounded or acute; surfaces abaxially whitish, densely covered with minute, compact, appressed, (8-)10-14(-16)-rayed stellate hairs less than 0.2 mm diam. (lateral fusion of rays visible under high magnification), without glandular seriate hairs, adaxially dull, light green, grayish, or yellowish green, with scattered, appressed-stellate hairs to 0.2 mm diam. |
blade usually strongly bicolored, oblong or elliptic, (15-)30-50(-80) × (10-)20-30(-35) mm, leathery, base rounded, rarely cuneate or cordulate, margins entire or toothed or denticulate, undulate or flat, secondary veins 8-9 on each side, apex rounded or acute; surfaces abaxially densely gray- or white-tomentose with semi-erect curly, stellate hairs, secondary veins rather prominently raised, adaxially dark or dull green, lustrous or somewhat glaucous, with minute, scattered, semi-erect or appressed-stellate, (4-)6 or many rayed hairs, not felty to touch, secondary veins slightly raised or prominent within depressions. |
Acorns | solitary or clustered, subsessile; cup deeply cup-shaped or turbinate, to 5-13 mm deep × 12-20 mm wide, scales whitish or cream, strongly tuberculate especially near base of cup; nut dark brown, fusiform or cylyndric, 20-30 × 10-30 mm. |
solitary or paired, subsessile or peduncle sometimes 10-15 mm, tomentose like twigs; cup shallowly to very deeply cup-shaped, 5-12 mm deep × 8-18 mm wide, enclosing 1/2 nut, base rounded or flat, margin thin, scales triangular-ovate to oblong, proximal scales coarsely tuberculate and canescent-tomentose, distal ones usually elongate and narrowed, tips appressed, reddish, thin, nearly glabrous; nut light brown, ellipsoid to ovoid, 8-15 × 5-12 mm. |
Cotyledons | distinct. |
connate. |
Quercus cornelius-mulleri |
Quercus mohriana |
|
Phenology | Flowering early spring. | Flowering spring. |
Habitat | Open chaparral, pinyon and juniper woodlands, desert margins, often on loose granitic soils | Limestone hills and slopes, calcareous substrates |
Elevation | 1000-1800 m (3300-5900 ft) | 600-2500 m (2000-8200 ft) |
Distribution |
CA; Mexico (Baja California)
|
NM; OK; TX; Mexico (Coahuila)
|
Discussion | Quercus cornelius-mulleri is easily distinguished from other California scrub oaks by the strongly bicolored leaves, dense minute tomentum of the abaxial leaf surface, and large acute acorns in deep tuberculate cups. Of greater difficulty are swarms of putative hybrids with Q. engelmannii, sometimes referred to as Q. ×acutidens. In Joshua Tree National Monument a lone tree and several shrubs appear to be hybrids and backcrosses between Quercus cornelius-mulleri and Q. lobata. This tree is the basis of Quercus ×munzii J. M. Tucker. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Putative hybrids between Quercus mohriana Buckley and Q. grisea Liebmann are problematic and highly polymorphic. They are restricted to zones of contact between limestone, the preferred habitat of Q. mohriana, and igneous substrates, the preferred habitat of Q. grisea, or sometimes on dolomite, in western Texas. (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 | ||
Name authority | Nixon & K. P. Steele: Madroño 28: 210. (1981) | Buckley: in Rydberg, Bull. New York Bot. Gard. 2: 219. (1901) |
Web links |