It is endemic to California, where it is known only from northern San Diego and southern Riverside Counties in the Peninsular Ranges.

[1] It was named for the community of Rainbow, California, near where it is most common in the chaparral of the lower elevation coastal Santa Ana Mountains, and the only manzanita species throughout most of its range.

The oval leaves are up to 5 centimeters long and 3.5 wide and are hairless and somewhat waxy in texture.

The inflorescence is a hanging cluster of white urn-shaped flowers each about 6 to 8 millimeters long.

Since the species was first collected its habitat has undergone extensive development, leading to the extirpation of many of its populations.