Island oak (Quercus tomentella), also known as island live oak or channel islands oak, is an evergreen tree in the Oak family (Fagacea). A smaller oak tree in stature, the leaves are hairy (tomentose) on the upper and lower surfaces, toothes, and large compared to other oaks. Young twigs are also hairy, yet mature bark is gray and furrowed. Mature acorns have rounded tips and are also quite large compared to other species.

Endemic (limited) to six islands off the coast of California, it is also federally listed as a rare species because of its limited distribution in the wild. Island oak's natural habitat is Island canyons, slopes and bluffs. Oak trees support a larger number of wildlife than any type of tree in our state. Multiple mammals, birds, amphibians, and pollinators use oak trees for food and shelter. Indigenous People ground the acorns to make flour, after leaching out the tannins; they may also have roasted and ground them and used it as a coffee alternative.

In the garden it is fast growing and trouble-free. It is best used near the coast, but can tolerate inland conditions within about 20 miles of the coast if given some protection and a little extra water during dry times, especially when the young plant is getting established. The large leaves and dense shade create unfavorable conditions for understory plants; plant island shrubs and perennials with similar growing conditions next to it, rather than under it for better results.