| Quercus tomentella | |
|---|---|
 | |
| island oak,Santa Rosa Island | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Fagales |
| Family: | Fagaceae |
| Genus: | Quercus |
| Subgenus: | Quercussubg. Quercus |
| Section: | Quercussect. Protobalanus |
| Species: | Q. tomentella |
| Binomial name | |
| Quercus tomentella | |
 | |
| Natural range ofQuercus tomentella | |
| Synonyms[2] | |
List
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Quercus tomentella, theisland oak,[3]island live oak,[4] orChannel Island oak,[5] is anoak in the sectionProtobalanus. It is native to six islands: five of theChannel Islands of California andGuadalupe Island, part ofBaja California.
It is placed inQuercus sectionProtobalanus.[6]
Island oak is atree growing up to 20 metres (66 feet) in height.[5] The mature tree has a grayish to reddish brown trunk with scaly, furrowedbark.[3] The twigs are reddish and covered in woolly hairs. The leatheryleaf blades are often concave and are an oblong lance shape or oval with pointed or rounded tips. The edges are smooth or toothed.[5] 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.[3] They are usually 7 to 10 centimetres (2+3⁄4 to 4 inches) long, sometimes up to12 cm (4+3⁄4 in). Theacorn grows singly or in pairs. The cup has thick scales and woolly hairs and is up to3 cm (1+1⁄8 in) wide. The nut is up to 3.5 cm with a rounded tip.[3][5]
It is native to six islands: five of theChannel Islands of California (Anacapa Island,San Clemente Island,Santa Catalina Island,Santa Cruz Island, andSanta Rosa Island) andGuadalupe Island, part of the State ofBaja California.[7]
This species is arelict. Though it is now limited to the islands, it was once widespread in mainland California, as evidenced by the manylate Tertiaryfossils of the species found there.[5] Recently, it was found that there was a high genetic variability across many of theQ. tomentella populations, but this variation was not evenly distributed.[8]
Island oakhybridizes withcanyon live oak (Quercus chrysolepis).[5]
The island oak was listed as anendangered species by theInternational Union for Conservation of Nature.[1]
The species is threatened byovergrazing from nonnative ungulates. The most rapid declines have occurred on Guadalupe Island.[1] The trees there are apparently no longer reproducing.[9]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 soilerosion. Fenced enclosures have been helpful in the early recovery of some of the local flora.[10]
