Quercus tomentella
Island oak, Island Oak
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Family: Fagaceae · Type: Tree · Native
Conservation status: CNPS 4.2
Quercus tomentella (Island oak) is a native California tree in the Fagaceae family, recognized by Channel Islands endemic with distinctly tomentose leaves.
Island oak is a native tree found in the Channel Islands at elevations below 600 meters in canyon and woodland habitats. Flowering from April to May, this tree produces small, unremarkable flowers characteristic of oak species. Growing up to 20 meters tall with an evergreen habit, it features a distinctive gray or red-brown trunk with deeply furrowed, scaly bark and tomentose (woolly) young twigs. Its leaves are oblong to oblong-ovate, 5 to 8 centimeters long, with a dark green upper surface that becomes glabrous with age and a densely tomentose, dull gray-green undersurface. The tree's acorn cup is 20 to 30 millimeters wide, with thick, tubercled scales, and the nut is widely ovoid, maturing in its second year.
Identification and appearance
Key characters: 15 sympatric species; Channel Islands endemic with distinctly tomentose leaves
Habitat and range
Habitat: Canyons, slopes, woodland
Elevation: < 600 m
California counties: Santa Barbara, Los Angeles, Ventura, San Diego
Outside California: Baja California (Guadalupe Island)
Bloom period
Quercus tomentella blooms Apr-May.
Conservation status
CNPS 4.2
How to tell it apart
vs Prunus: Quercus has acorns in cups; cherries/plums have fleshy round fruits.; vs Notholithocarpus: Quercus has drooping catkins; tanoak has upright flower spikes.; vs Rhamnus: Quercus has acorns; buckthorns have berry-like fruits.; vs Ceanothus: Quercus has acorns; California lilacs have small capsule fruits.; vs Platanus: Quercus has acorns; sycamores have hanging ball-shaped seed clusters.
Frequently asked questions
Is Quercus tomentella native to California?
Yes. Quercus tomentella is native to California (recorded as native).
When does Quercus tomentella bloom?
Quercus tomentella blooms Apr-May.
Where in California does Quercus tomentella grow?
Quercus tomentella occurs in Santa Barbara, Los Angeles, Ventura, San Diego, at elevations of < 600 m.
What plant family does Quercus tomentella belong to?
Quercus tomentella is in the Fagaceae family, genus Quercus.
Is Quercus tomentella rare or endangered?
Quercus tomentella carries California Rare Plant Rank 4.2, state rank S3S4.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.