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

oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...

in the section ''Protobalanus''. It is native to six islands: five of 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. They define the Santa Barbara Channel between the islands and the California mainland. The ...

and

Guadalupe Island Guadalupe Island () 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 various volcanoes are extinc ...

, part of

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

. It is placed in ''Quercus'' section ''Protobalanus''.

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, e.g., including only woody plants with secondary growth, only ...

growing up to in height. The mature tree has a grayish to reddish brown trunk with scaly, furrowed

bark Bark may refer to: Common meanings * 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) Arts and entertainment * ''Bark'' (Jefferson Airplane album), ...

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

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

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 is the nut (fruit), nut of the oaks and their close relatives (genera ''Quercus'', ''Notholithocarpus'' and ''Lithocarpus'', in the family Fagaceae). It usually contains a seedling surrounded by two cotyledons (seedling leaves), en ...

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

(

Anacapa Island Anacapa Island ( Chumash: ''Anyapax'', meaning "mirage, illusion") is a small volcanic island located about off Port Hueneme in Ventura County, California. The island is composed of a series of narrow islets long, oriented generally east� ...

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 administer ...

, Santa Catalina Island,

Santa Cruz Island Santa Cruz Island (Spanish language, Spanish: ''Isla Santa Cruz'', Chumashan languages, Chumash: ''Limuw'') is located off the southwestern coast of Ventura, California, United States. It is the largest island in California and largest of the ei ...

, 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 The Neogene ( ,) is a Geologic time scale#Terminology, geologic period and system that spans 20.45 million years from the end of the Paleogene Period million years ago (Year#Abbreviations yr and ya, Mya) to the beginning of the present Quatern ...

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 preserve ...

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'').

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, inv ...

by the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

. 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 ...

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 goat The feral goat is the domestic goat (''Capra hircus'') when it has become established in the wild. Feral goats occur in many parts of the world. Species Feral goats consist of many breeds of domestic goats, all of which stem from the wild go ...

s 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 Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

. 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 Natural history of the Channel Islands of California Natural history of the California chaparral and woodlands Trees of Northern America Trees of mild maritime climate Trees of Mediterranean climate Garden plants of North America Drought-tolerant trees Ornamental trees Oaks of Mexico Trees of Mexican Pacific Islands Flora of Guadalupe Island