Located in the transition zone between the San Gabriel Mountains' California chaparral and woodlands Ecosystem, and the Mojave's Deserts and xeric shrublands Biome in the California Floristic Province, the Placerita Canyon Flora is complex. Placerita Canyon State Park is in the east-west trending Placerita Canyon on the Placerita Fault and contains sandstone and metamorphic formations, and seasonal streams. Chaparral, Riparian, and Coast Live Oak woodland plant communities are represented, including willows, cottonwoods and native California Sycamore trees.