Quercus pacifica |
Quercus rugosa |
|
---|---|---|
Channel Island scrub oak, island scrub oak, Pacific oak |
netleaf oak |
|
Habit | Shrubs, rarely small trees, subevergreen, shrubs to 2 m, trees to 5 m or taller. | Shrubs or trees, evergreen, usually moderate-sized, rarely large. |
Bark | scaly on older branches and trunk. |
light or dark brown, scaly. |
Twigs | brownish or reddish, minutely puberulent, becoming glabrate and gray with age. |
brown, turning gray with age, 1-2 mm diam., tomentose to tomentulose, variously glabrate or persistently pubescent. |
Buds | light or chestnut brown, ovate or globose, 2-3 × 1-2 mm. |
brown, ovoid, 2-4 mm, apex obtuse, sparsely pubescent or eventually glabrate. |
Leaves | blade obovate or oblong, planar to moderately convex or undulate, 15-40 × 7-20(-40) mm, base cuneate or rounded, attenuate-decurrent along petiole, margins minutely cartilaginous, entire or with 1-5 irregular teeth on each side, secondary veins obscure, 1-5 on each side, apex blunt or rounded, occasionally subacute with mucronate tip; surfaces abaxially waxy, glandular, with scattered minute, flat, appressed, ± 8-rayed stellate hairs, not obscuring surface, adaxially green, glossy, glabrate or with minute, scattered, stellate hairs. |
blade broadly obovate or panduriform to orbiculate or elliptic, rarely narrowly obovate, usually cupped, strongly concave proximally, sometimes planar, to 100 × 70 mm, stiff, leathery, base deeply or shallowly cordate, margins usually somewhat revolute, cartilaginously thickened, undulately crisped or flat with inconspicuous or coarse mucronate teeth near apex, secondary veins 8-10(-12) on each side, branched, apex broadly rounded, rarely subacute; surfaces abaxially dull, glaucous, or densely brownish tomentose, becoming nearly glabrate or pubescence persistent, especially about midribs, secondary veins very prominently raised, reticulate, adaxially dark green, lustrous, sparsely stellate-pubescent especially about base of midrib, secondary veins impressed. |
Acorns | paired or solitary in leaf axil, subsessile, rarely pedunculate in teratological forms; cup hemispheric to turbinate, to 15 mm deep × 20 mm wide, enclosing only 1/4-1/2 nut, scales moderately to heavily tuberculate, irregularly formed; nut light brown, acute-cylindric or fusiform, tapered, (15-)20-30 × (6-)9-15 m, apex acute, glabrate. |
1-3 or more on slender axillary peduncle 30-60 mm; cup deeply cup-shaped to saucer-shaped, to 9 mm deep × 15 mm wide, enclosing to 1/2 nut, scales loosely appressed, characteristically somewhat spreading, brown, ovate, tuberculate-thickened or only slightly so, tomentose or obscurely tomentulose; nut light brown, ovoid to elliptic, to 20 × 15 mm, glabrous or minutely villous. |
Cotyledons | distinct. |
distinct, often reddish or purple. |
Quercus pacifica |
Quercus rugosa |
|
Phenology | Flowering spring. | Flowering early–late spring. |
Habitat | Chaparral, oak woodlands, margins of grasslands, understory in closed-cone pine stands | Wooded slopes |
Elevation | 0-300 m (0-1000 ft) | 2000-2500 m (6600-8200 ft) |
Distribution |
CA
|
AZ; NM; TX; Mexico; Central America (Guatemala)
|
Discussion | Of conservation concern. Quercus pacifica is endemic on three of the California Channel Islands: Santa Cruz, Santa Catalina, and Santa Rosa. It is not known from the mainland, but it bears a superficial similarity to some of the tree forms that are putative hybrids between Q. engelmannii and Q. cornelius-mulleri in San Diego County. The latter populations, sometimes treated as Q. ×acutidens, differ in having much greater variability in leaf shape; thicker, more leathery leaves; denser abaxial leaf vestiture; much smaller hairs, having more than 10 rays; and variable levels of connation of cotyledons (always distinct in Q. pacifica). Quercus pacifica appears to be most closely related to Q. douglasii, whether by direct descent or by introgression with another species no longer extant on the islands. Quercus ×macdonaldii Greene (as a species) [= Quercus dumosa var. macdonaldii (Greene) Jepson] is a stabilized hybrid complex between Quercus pacifica and Q. lobata Née. The plants tend to be small to moderate trees with leaves that resemble those of Q. lobata; the leaves are much more shallowly lobed and always less than two-thirds the distance from the margin to the midrib. Quercus ×macdonaldii is known from Santa Rosa, Santa Cruz, and Santa Catalina islands. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Quercus rugosa occurs on wooded slopes at high elevations in trans-Pecos Texas, southern New Mexico, and Arizona, and throughout most of the mesic montane parts of Mexico, south to Guatemala. (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. dumosa var. polycarpa | Q. ariifolia, Q. diversicolor, Q. durangensis, Q. reticulata, Q. rhodophlebia, Q. vellifera |
Name authority | Nixon & C. H. Muller: Novon 4: 391. (1994) | Nee.: Anales Ci. Nat. 3: 275. (1801) |
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