''Quercus pacifica'' is a species of

oak An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably ''L ...

known by the common names island scrub oak, Channel Island scrub oak, and Pacific oak.

Description

''Quercus pacifica'' is a shrub or a small

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

growing up to in height, or occasionally taller. The leaves are roughly oval in shape and edged with pointed teeth. The green blades are up to long by 4 cm wide. They have shiny upper surfaces and waxy, hairy, glandular undersides. The

acorn The acorn, or oaknut, is the nut of the oaks and their close relatives (genera '' Quercus'' and ''Lithocarpus'', in the family Fagaceae). It usually contains one seed (occasionally two seeds), enclosed in a tough, leathery shell, and bo ...

has a cap up to wide and a nut measuring long. Quercus pacifica 3

This oak often produces a stable

hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two diff ...

with ''

Quercus lobata ''Quercus lobata'', commonly called the valley oak or roble, grows into the largest of California oaks. It is endemic to California, growing in interior valleys and foothills from Siskiyou County to San Diego County. Mature specimens may attain ...

'', that has been named '' Quercus'' × ''macdonaldii''.

Distribution

It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...

to the

Channel Islands of California The Channel Islands () are an eight-island archipelago located within the Southern California Bight in the Pacific Ocean, off the coast of California. The four Northern Channel Islands are part of the Transverse Ranges geologic province, ...

, where it is known from the islands of Santa Cruz, Santa Rosa, and Santa Catalina. The islands of Santa Cruz and Santa Rosa are part of

Channel Islands National Park Channel Islands National Park consists of five of the eight Channel Islands off the Pacific coast of the U.S. state of California. Although the islands are close to the shore of the densely populated state, they have been relatively undeveloped ...

. Though limited to three islands, it is not uncommon there, occurring in

grassland A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur natur ...

chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterrane ...

, oak woodlands, forest, and other habitat. It is the dominant oak in many areas on Catalina Island.Knapp, D. A. (2002)
The Status of Island Scrub Oak (''Quercus pacifica'') on Catalina Island, California.
In: Standiford, R. B., et al. Proceedings of the Fifth Symposium on Oak Woodlands: Oaks in California's Challenging Landscape. Gen. Tech. Rep. USDA Forest Service. It was described as a new species in 1994 from a specimen collected on Santa Cruz Island. More than a century earlier, the same plant was described as a variety of ''Quercus dumosa''; the 1994 name is nevertheless the correct name for the plant when recognized as a species because names hold priority status only within a given rank.

Threats

This oak species is threatened by a pathogenic

honey fungus ''Armillaria'' is a genus of fungi that includes the '' A. mellea'' species known as honey fungi that live on trees and woody shrubs. It includes about 10 species formerly categorized summarily as ''A. mellea''. ''Armillarias'' are long-l ...

(''

Armillaria ''Armillaria'' is a genus of fungi that includes the '' A. mellea'' species known as honey fungi that live on trees and woody shrubs. It includes about 10 species formerly categorized summarily as ''A. mellea''. ''Armillarias'' are long-l ...

'' sp.), which has been noted to infect trees already stressed by the activity of feral herbivores, including

goats The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of the a ...

and

pigs The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus ''Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus ...

. A new species of fungus was discovered growing in

oak galls Oak apple or oak gall is the common name for a large, round, vaguely apple-like gall commonly found on many species of oak. Oak apples range in size from in diameter and are caused by chemicals injected by the larva of certain kinds of gal ...

on this oak species and was named '' Penicillium cecidicola'' in 2004.Seifert, K. A., et al. (2004)
''Penicillium cecidicola'', a new species on cynipid insect galls on ''Quercus pacifica'' in the western United States.
''Studies in Mycology'' 50 517-23.

References

External links

*
The Nature Conservancy
* {{Taxonbar, from=Q7271346 pacifica Endemic flora of California Natural history of the California chaparral and woodlands Natural history of the Channel Islands of California Plants described in 1994 Channel Islands National Park