Notholithocarpus densiflorus
Tanoak
(c) Adam J. Searcy, some rights reserved (CC BY) · licence
Family: Fagaceae · Type: Shrub / Tree · Native
Notholithocarpus densiflorus (Tanoak) is a native California shrub / tree in the Fagaceae family, recognized by varieties differ primarily in leaf size and habitat elevation.
Tanoak is a native shrub or tree found in California's coastal ranges and Sierra Nevada foothills in mixed evergreen and conifer forests, typically growing at moderate elevations. Flowering from spring to early summer, this plant produces small greenish-yellow flowers in dense, stiff spikes. Growing to 30 meters tall with a gray-brown trunk, it develops an evergreen form with spreading branches. Its leathery leaves are oblong to slightly ovate, 3 to 14 centimeters long, with entire to slightly serrated edges and a fine woolly undersurface that becomes smoother with age. The distinctive acorn-like fruit develops in a saucer-shaped cup 2 to 3 centimeters wide, with a single nut 20 to 35 millimeters long that matures in its second year.
Identification and appearance
Key characters: Geographically isolated genus with no sympatric congeners; varieties differ primarily in leaf size and habitat elevation
Habitat and range
California counties: Humboldt, Santa Barbara, San Mateo, Mendocino, Santa Cruz, San Luis Obispo, Monterey, Sierra, Siskiyou, Marin, Yuba, Shasta, Del Norte, Trinity, Ventura, El Dorado, Butte, Sonoma, Santa Clara, Mariposa, Plumas, Placer, Napa
How to tell it apart
vs Quercus: Notholithocarpus has erect flower spikes; oak catkins hang downward.; vs Heteromeles: Notholithocarpus has acorns in cups; toyon has red berry clusters.; vs Frangula: Notholithocarpus has acorns; Frangula has smooth berry-like fruits.; vs Chrysolepis: Notholithocarpus has cup-scaled acorns; Chrysolepis nuts are in spiny burs.; vs Alnus: Notholithocarpus has acorns; alders have small woody cones.
Frequently asked questions
Is Notholithocarpus densiflorus native to California?
Yes. Notholithocarpus densiflorus is native to California (recorded as native).
Where in California does Notholithocarpus densiflorus grow?
Notholithocarpus densiflorus occurs in Humboldt, Santa Barbara, San Mateo, Mendocino, Santa Cruz, San Luis Obispo, Monterey, Sierra and other counties.
What plant family does Notholithocarpus densiflorus belong to?
Notholithocarpus densiflorus is in the Fagaceae family, genus Notholithocarpus.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
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.