Quercus pacifica |
Quercus chapmanii |
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Channel Island scrub oak, island scrub oak, Pacific oak |
Chapman oak, Chapman's oak |
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Habit | Shrubs, rarely small trees, subevergreen, shrubs to 2 m, trees to 5 m or taller. | Shrubs, deciduous or subevergreen, 0.5-3(-6) m, often rhizomatous. |
Bark | scaly on older branches and trunk. |
brown, scaly. |
Twigs | brownish or reddish, minutely puberulent, becoming glabrate and gray with age. |
yellowish, 1-2 mm diam., densely fine-tomentulose. |
Buds | light or chestnut brown, ovate or globose, 2-3 × 1-2 mm. |
reddish brown, globose, 1-2(-3) mm, proximal scales densely tomentulose, distal scales glabrous. |
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 obovate or oblanceolate, 30-70(-85) × 14-30(-45) mm, base cuneate or attenuate, margins minutely revolute, entire or sinuately lobed, sometimes obscurely 3-lobed distally or with 3-5 rounded, irregular lobes in distal 1/2, secondary veins curved, 8-9 on each side, apex ovate or triangular-lobed, often retuse; surfaces abaxially grayish or yellowish, with yellowish, erect branched hairs, these soon shed, leaving matted glandular and waxy hairs except on ± glabrate yellowish veins, adaxially bright glossy, very reflective, glabrous or with minute, scattered, stellate hairs. |
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. |
1-2, on peduncle 1-6(-35) mm; cup hemispheric, 5-11 m deep × 10-15 mm wide, including 1/3-1/2 nut, scales closely appressed, gray, tomentulose; nut light brown, ovoid to barrel-shaped, 15-20 × 9-13 mm, apex rounded, glabrous or puberulent. |
Cotyledons | distinct. |
distinct. |
Quercus pacifica |
Quercus chapmanii |
|
Phenology | Flowering spring. | Flowering late winter–early spring. |
Habitat | Chaparral, oak woodlands, margins of grasslands, understory in closed-cone pine stands | Open pine forests, scrublands, xerophytic scrub oak, on sand near coast |
Elevation | 0-300 m (0-1000 ft) | 0-100 m (0-300 ft) |
Distribution |
CA
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FL; GA; SC
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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.) |
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Source | FNA vol. 3. | FNA vol. 3. |
Parent taxa | Fagaceae > Quercus > sect. Quercus | Fagaceae > Quercus > sect. Quercus |
Sibling taxa | ||
Synonyms | Q. dumosa var. polycarpa | |
Name authority | Nixon & C. H. Muller: Novon 4: 391. (1994) | Sargent: Gard. & Forest 8: 93. (1895) |
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