American subevergreen oak complex

Quercus agrifolia, the coast live oak or California live oak, is a live oak (a semi-evergreen oak) native to the California Floristic Province. Live oaks are so-called because they keep living leaves on the tree all year, adding young leaves and shedding dead leaves simultaneously rather than dropping dead leaves en masse in the autumn like a true deciduous tree. The coast live oak may be shrubby, depending on age and growing location, but is generally a medium-sized tree. It grows west of the Sierra Nevada mountain range from Mendocino County, California, south to northern Baja California in Mexico. It is classified in the red oak section of oaks (Quercus sect. Lobatae), subsection Agrifoliae.

This species is commonly sympatric with canyon live oak (Q. chrysolepis), and the two may be hard to distinguish because their spinose leaves are superficially similar.