Notholithocarpus densiflorus, commonly known as the tanoak or tanbark-oak, is an evergreen tree in the beech family (Fagaceae), native to the western United States, in California as far south as the Transverse Ranges, north to southwest Oregon, and east in the Sierra Nevada. It can reach 40 m (130 ft) tall (though 15–25 m (49–82 ft) is more usual) in the California Coast Ranges, and can have a trunk diameter of 60–190 cm (24–75 in).