Muhlenbergia californica is an uncommon species of grass known by the common name California muhly. It is endemic to California Transverse Ranges, where it is known only from the San Bernardino Mountains in Southern California. It grows in moist habitat, such as streambanks and ditches, in the chaparral and woodlands. Muhlenbergia californica is a rhizomatous perennial grass growing 30 to 70 centimeters tall. The inflorescence is a narrow array of thin branches bearing many tiny pointed or awned hairy spikelets each a few millimeters long.