O. californica

O. californica may refer to:
 * Oenothera californica, the California evening primrose, a flowering plant species native to parts of the southwestern United States and Baja California
 * Orcuttia californica, the California Orcutt grass, a rare grass species native to southern California and northern Baja California
 * Orobanche californica, the California broomrape, a plant species native to western North America
 * Osmia californica, a mason bee species native to North America