Quercus pacifica is a species of oak known by the common names island scrub oak and Pacific oak. It is endemic to the Channel Islands of California, where it is known from Santa Cruz, Santa Rosa, and Santa Catalina Islands. Though limited to three islands, it is not uncommon there, occurring in grassland, chaparral, oak woodlands, forest, and other habitat. It is the dominant oak in many areas on Catalina Island.It was described as a new species in 1994 from a specimen on Santa Cruz Island.This is a shrub or a small tree growing up to five meters in height, or occasionally taller. The leaves are roughly oval in shape and edged with pointed teeth. The green blades are up to 4 centimeters long by 4 wide. They have shiny upper surfaces and waxy, hairy, glandular undersides. The acorn has a cap up to 2 centimeters wide and a nut measuring 2 or 3 centimeters long.