''Quercus tomentella'', the island oak, island live oak, or Channel Island oak, is an

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 ...

in the section ''Protobalanus''. It is native to six islands: five of the Channel Islands of California and

Guadalupe Island Guadalupe Island ( es, Isla Guadalupe, link=no) is a volcanic island located off the western coast of Mexico's Baja California Peninsula and about southwest of the city of Ensenada in the state of Baja California, in the Pacific Ocean. The ...

, part of

Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...

Description

Island oak is a

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. The mature tree has a grayish to reddish brown trunk with scaly, furrowed

bark Bark may refer to: * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Places * Bark, Germany * Bark, Warmian-Masurian Voivodeship, Poland Arts, ...

. The twigs are reddish and covered in woolly hairs. The leathery

leaf A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...

blades are often concave and are an oblong lance shape or oval with pointed or rounded tips. The edges are smooth or toothed. The upper surfaces are dark green and lightly hairy when new, losing the hairs over time. The undersides are gray-green and coated in woolly hairs, becoming less woolly with age. They are usually long, sometimes up to . 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 borne ...

grows singly or in pairs. The cup has thick scales and woolly hairs and is up to wide. The nut is up to 3.5'' ''cm with a rounded tip.

Distribution and habitat

It is native to six islands: five of the Channel Islands of California ( Anacapa Island,

San Clemente Island San Clemente Island (Tongva: ''Kinkipar''; Spanish: ''Isla de San Clemente'') is the southernmost of the Channel Islands of California. It is owned and operated by the United States Navy, and is a part of Los Angeles County. It is administered b ...

, Santa Catalina Island,

Santa Cruz Island Santa Cruz Island (Spanish: ''Isla Santa Cruz'', Chumash: ''Limuw'') is located off the southwestern coast of Ventura, California, United States. It is the largest island in California and largest of the eight islands in the Channel Islands a ...

, and Santa Rosa Island) and

, part of the State of

. This species is a

relict A relict is a surviving remnant of a natural phenomenon. Biology A relict (or relic) is an organism that at an earlier time was abundant in a large area but now occurs at only one or a few small areas. Geology and geomorphology In geology, a r ...

. Though it is now limited to the islands, it was once widespread in mainland California, as evidenced by the many late Tertiary

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s of the species found there. Recently, it was found that there was a high genetic variability across many of the ''Q. tomentella'' populations, but this variation was not evenly distributed.

Ecology

Island oak hybridizes with

canyon live oak ''Quercus chrysolepis'', commonly termed canyon live oak, canyon oak, golden cup oak or maul oak, is a North American species of evergreen oak that is found in Mexico and in the western United States, notably in the California Coast Ranges. This ...

(''Quercus chrysolepis'').

Conservation

The island oak was listed as an

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

by the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

. The species is threatened by

overgrazing Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature res ...

from nonnative ungulates. The most rapid declines have occurred on Guadalupe Island. The trees there are apparently no longer reproducing.de la Luz, J. L. L., et al. (2003)
On the urgency of conservation on Guadalupe Island, Mexico: is it a lost paradise?
''Biodiversity and Conservation'' 12(5), 1073-82. Feral goats have been abundant on the island for at least 150 years. The animals have eliminated much of the native vegetation and caused extensive soil

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

. Fenced enclosures have been helpful in the early recovery of some of the local flora.Junak, S., et al. (2003)
Esfuerzos recientes de conservación y apuntes sobre el estado actual de la flora de Isla Guadalupe, Baja California, México.
(Spanish) Presentation at ''Taller sobre la Restauración y Conservación de Isla Guadalupe'' orkshop on Restoration and Conservation of Guadalupe Island Instituto Nacional de Ecología, November 13–14, 2003
HTML abstract
(English)

References

External links

* *
photo of herbarium specimen at Missouri Botanical Garden, collected in Guadalupe Island in 1875
{{Taxonbar, from=Q2715180

tomentella ''Tomentella'' is a genus of corticioid fungi in the family Thelephoraceae. The genus is ectomycorrhizal, and widespread, with about 80 species according to a 2008 estimate, although many new species have since been described. ''Tomentella'' was ...

Flora of California Trees of Baja California Natural history of the Channel Islands of California Natural history of the California chaparral and woodlands Trees of the Southwestern United States Trees of mild maritime climate Trees of Mediterranean climate Garden plants of North America Drought-tolerant trees Ornamental trees Oaks of Mexico