Quercus pacifica |
Quercus berberidifolia |
|
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Channel Island scrub oak, island scrub oak, Pacific oak |
California scrub oak, inland scrub oak, scrub oak |
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Habit | Shrubs, rarely small trees, subevergreen, shrubs to 2 m, trees to 5 m or taller. | Shrubs, subevergreen, 1-2(-4) m. Bark gray, scaly. |
Bark | scaly on older branches and trunk. |
|
Twigs | brownish or reddish, minutely puberulent, becoming glabrate and gray with age. |
gray, yellowish, rarely reddish, 1-3 mm diam. |
Buds | light or chestnut brown, ovate or globose, 2-3 × 1-2 mm. |
reddish brown, globose or ovoid, 2-3 mm, minutely puberulent. |
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 bicolored, obovate, elliptic, occasionally subrotund, planar or moderately convex, (10-)15-30 × (8-)10-20 mm, base truncate or rounded-attenuate, rarely cuneate, margins irregularly toothed and spinose, often sublobate, rarely entire, secondary veins (3-)4-7 on each side, apex broadly rounded or acute; surfaces abaxially waxy, light green or glaucous, with scattered minute, appressed, (4-)8(-10)-rayed hairs less than 0.2 mm diam. and sparse to dense yellowish, glandular hairs, adaxially glossy or dull green, glabrous or glabrate. |
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. |
solitary or paired, subsessile; cup hemispheric or turbinate, rarely shallowly cup-shaped, rim thick, 8-15 mm deep × 15-20(-22) mm wide, enclosing to 1/2 nut, scales reddish or yellowish, usually strongly, irregularly tuberculate, puberulent or canescent; nut light to dark brown, ovoid, ellipsoid, or barrel-shaped, (10-)15-30 × (8-)10-20 mm, apex rounded, glabrous at maturity. |
Cotyledons | distinct. |
distinct. |
Quercus pacifica |
Quercus berberidifolia |
|
Phenology | Flowering spring. | Flowering spring. |
Habitat | Chaparral, oak woodlands, margins of grasslands, understory in closed-cone pine stands | Chaparral, margins of coastal sage scrub |
Elevation | 0-300 m (0-1000 ft) | 100-1800 m (300-5900 ft) |
Distribution |
CA
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CA
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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.) |
The name Quercus dumosa (see species treatment no. 72) has often been applied to this species. Quercus berberidifolia is the most common scrub oak of central and southern California, mostly at midelevations in the Coast Ranges. In central California it is replaced in drier interior habitats by Q. john-tuckeri, and south of the transverse ranges by Q. cornelius-mulleri. From Santa Barbara south, it does not descend to the low elevation coastal sites typical of Q. dumosa in the strict sense. Quercus berberidifolia hybridizes with numerous other white oaks of California. In southern California, putative hybrids with Q. john-tuckeri are noticeable in the mountains above Ventura and on the north slope of the Tehachapi Mountains. (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. agrifolia var. berberidifolia, Q. dumosa var. munita |
Name authority | Nixon & C. H. Muller: Novon 4: 391. (1994) | Liebmann: Overs. Kongel. Danske Vidensk. Selsk. Forh. Medlemmers Arbeider 1854: 172. (1854) |
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