Quercus tomentella |
Quercus laceyi |
|
---|---|---|
Channel Island oak, island live oak, island oak |
lacey oak |
|
Habit | Trees, to 20 m. Twigs branching at 45° angles, reddish brown, 3-4 mm diam., somewhat rigid, densely tomentose, persistent into 2d year. | Trees, deciduous, to 5-8(-10) m. Bark light colored, papery or scaly. |
Twigs | gray, 1.5-2 mm diam., pubescent with erect stellate hairs, these soon shed, at maturity reddish and pruinose to tan and glabrous. |
|
Buds | brown, ovoid to ovoid-lanceoloid, 1.5-3 × 1-2 mm, apex acute, glabrous. |
|
Leaves | blade wavy or distinctly concave, oblong-lanceolate or elliptic, acuminate, (30-)70-10(-120) × 25-40 mm, leathery and brittle, base obtuse to cordate, secondary veins 8-10(-12) pairs, branching at 45-50° angles, strongly pinnate, raised abaxially, often sunken adaxially, margins often strongly revolute, with slightly thickened cell walls, entire or crenate to dentate with mucronate teeth, apex rounded or acute, mucronate; surfaces abaxially densely tomentose with whitish nonglandular hairs, midrib pilose, adaxially glossy dark green, sparsely pubescent. |
blade blue-green, glaucous, obovate or elliptic, (20-)40-90(-210) × (20-)30-60(-110) mm, thin, base cuneate and decurrent on petiole to rounded or rarely somewhat cordate, margins thin, flat, entire to shallowly lobed or (rarely in shade forms) deeply lobed, lobes if present oblong, squarish, often retuse, secondary veins 6-9 on each side, each terminating in tooth or arching near margins, apex broadly rounded, retuse; surfaces abaxially whitish, with erect stellate hairs, hairs shed as leaves expand, becoming glabrous, glaucous, adaxially glabrous, glaucous. |
Acorns | solitary or rarely paired; cup shallowly cup-shaped, 4-8 mm deep × 15-30 mm wide, scales laterally connate, appressed, deeply imbedded in tomentum, with only thin, brown, elongated apices visible, tuberculate, densely whitish brown tomentose throughout; nut ovoid, 20-30 × 15-20 mm, apex rounded. |
annual, solitary or paired, subsessile or on short peduncle to 10(-20) mm in leaf axil; cup saucer-shaped or shallowly cup-shaped, 4-7 mm deep × 10-12(-18) mm wide, enclosing 1/3 nut or less, scales moderately tuberculate, finely tomentose; nut oblong or barrel-shaped, often flattened at both ends, (11-)13-15(-20) × 9-11(-14) mm. |
Cotyledons | distinct. |
|
Terminal | buds conic, 7-10 mm, scales brown with ciliate margins. |
|
Quercus tomentella |
Quercus laceyi |
|
Phenology | Flowering in spring, occasionally in fall. | Flowering in spring. |
Habitat | Lower portions of steep canyons and occasionally ridge tops | Limestone hills, woodlands and riparian forests, canyons and streamsides |
Elevation | 100-650 m (300-2100 ft) | 350-2200 m (1100-7200 ft) |
Distribution |
CA; Mexico (Baja California and on Guadalupe Island)
|
TX; Mexico (Coahuila and Nuevo León) |
Discussion | The insular endemic Quercus tomentella is a relict as evidenced by its widespread representation in mainland late Tertiary fossil floras. Hybridization with Q. chrysolepis is apparent on the Channel Islands: Santa Catalina, Santa Cruz, and possibly San Clemente and Anacapa. Putative hybrids have been observed in narrow zones of contact on the islands of Santa Cruz and Santa Catalina. On those islands, taxonomically distinct individuals of Q. chrysolepis occur at the highest elevations, whereas Q. tomentella generally is found in moist canyons at lower elevations. Populations of Channel Island oak are in decline because of overgrazing and poor seedling recruitment. The greatest number of populations occur on Santa Rosa Island, and those are taxonomically and genetically noteworthy because Q. chrysolepis apparently is absent from the island. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Material from Texas and northeastern Mexico, excluding the type, has been incorrectly referred to Quercus glaucoides M. Martens & Galeotti by some authors (K. C. Nixon and C. H. Muller 1992). On the Edwards Plateau of Texas, Quercus laceyi occurs mostly at 350-600 m elevation; in Coahuila and Nuevo León, it occurs at 1500-2200 m. This species is sometimes associated with remnant mesic forests, which include Acer grandidentatum Nuttall, Tilia species, Quercus muhlenbergii Engelmann, and various pine and other oak species. The leaves are shallowly lobed or entire, although occasional specimens on moist sites are deeply lobed and resemble the leaves of Q. alba in outline. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 3. | FNA vol. 3. |
Parent taxa | Fagaceae > Quercus > sect. Protobalanus | Fagaceae > Quercus > sect. Quercus |
Sibling taxa | ||
Synonyms | Q. breviloba subsp. laceyi | |
Name authority | Engelmann: Trans. Acad. Sci. St. Louis, 3: 393. (1877) | Small: Bull. Torrey Bot. Club 28: 358. (1901) |
Web links |