Quercus lobata |
Quercus chihuahuensis |
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California white oak, roble, valley oak |
Chihuahua oak, Chihuahuan oak, felt oak |
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Habit | Trees, deciduous, to 25(-35) m, usually with solitary trunks. | Shrubs or trees, deciduous, to 10 m. Bark gray, furrowed, checkered, or scaly. |
Bark | gray, scaly, deeply checkered in age. |
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Twigs | yellowish, gray, occasionally reddish, 2-4 mm diam., densely or sparsely tomentulose. |
gray, 2-3(-4) mm diam., densely tomentose. |
Buds | yellowish or light brown, ovoid, (2-)3-5(-6) mm, apex occasionally acute, densely pubescent. |
reddish brown, broadly ovoid, distally rounded, 2-2.5 mm, densely yellowish pubescent; scales gray-puberulent; stipules persistent, 1-4, subulate, pubescent, at base of terminal buds. |
Leaves | blade broadly obovate or elliptic, moderately to deeply lobed, (40-)50-100(-120) × 30-60(-75) mm, base rounded-attenuate, cuneate, or truncate, rarely subcordate, margins with sinuses usually reaching more than 1/2 distance to midrib, lobes oblong or spatulate, obtuse, rounded, or blunt, secondary veins 5-10 on each side, apex broadly rounded; surfaces abaxially whitish or light green, densely to sparsely covered with interlocking appressed or semi-erect, 8-10(-14)-rayed stellate hairs, adaxially dark green or grayish, glossy or somewhat scurfy because of sparse stellate hairs. |
blade elliptic or oblong to ovate or obovate, (25-)40-50(-85) × (18-)20-30(-50) mm, base rounded or shallowly cordate, margins entire or toothed to sublobate, secondary veins 8 to 10 on each side, somewhat branching, apex broadly rounded to acute; surfaces abaxially yellowish or grayish, densely stellate with velvety hairs, adaxially green, sparsely soft-pubescent with prominent, spreading, stellate hairs, felty to touch, secondary veins somewhat prominent on both surfaces, even under dense tomentum. |
Acorns | solitary or paired, subsessile; cup deeply cup-shaped, hemispheric or turbinate, rim thick, 10-30 mm deep × 14-30 mm wide, scales grayish or cream, more acute near rim, strongly and irregularly tuberculate, especially toward base of cup; nut light brown, oblong or fusiform, 30-60 × (12-)15-25 mm, tapering to acute or rounded apex. |
1-3 on tomentose peduncle 15-35(-60) mm; cup hemispheric, 7-10 mm deep × 10-15 mm wide, enclosing 1/2 nut, scales proximally thickened, distally appressed, densely gray-puberulent, tips reddish, ultimately glabrate; nut ovoid, 14-18 × 10-12 mm, puberulent, eventually glabrate. |
Cotyledons | distinct. |
connate. |
Quercus lobata |
Quercus chihuahuensis |
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Phenology | Flowering late winter–early spring. | Flowering spring. |
Habitat | Valley floors and moderate slopes, open grasslands, savannah and oak woodlands, riparian areas in chaparral | Oak and pinyon-juniper woodlands, grassy hills, sometimes extending into dry thorn scrub and bursera woodland (Mexico) |
Elevation | 0-1700 m (0-5600 ft) | 400-2000 m (1300-6600 ft) |
Distribution |
CA
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TX; Mexico (Chihuahua, Sonora, Zacatecas, and San Luis Potosí)
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Discussion | Mature trees of Quercus lobata are among the largest oaks of the United States. The species hybridizes with numerous other species, but the hybrids are not common in most parts of its range. On Santa Cruz and Santa Catalina islands, however, occur extensive and relatively stable populations that show intermediate characteristics with Q. pacifica (see treatment). The hybrids have been given the name Q. ×macdonaldii, and they differ from Q. lobata in the following: leaf sinuses reaching less than half the distance to the midrib; leaves usually smaller, the lobes often more acute and brighter green; and acorns smaller, with more acute apices. The Yuri used Quercus lobata in the treatment of diarrhea (D. E. Moerman 1986). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Quercus chihuahuensis is a distinctive species throughout its range, mostly in dry montane western Mexico; it occurs in the United States only as putative hybrids with Q. grisea (the Eagle and Quitman mountains) and Q. arizonica (Hueco Tanks) in 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 | ||
Synonyms | Q. hindsii, Q. lobata var. hindsii, Q. longiglanda | Q. infralutea, Q. jaliscensis, Q. santaclarensis |
Name authority | Nee.: Anales Ci. Nat. 3: 277. (1801) | Trelease: Mem. Natl. Acad. Sci. 20: 85. (1924) |
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