Peninsular Ranges of San Diego and Riverside County .
Five occurrences on Conserved Lands in MUs 8 (BLM, Margarita Peak, Rock Mountain Preserve, Santa Margarita River Park) and 9 (Cleveland National Forest).
Granitic outcrops and chaparral . Elevation range is 150-800 meters.
Ericaceae family . Previously called A. peninsularis ssp. peninsularis or considered a hybrid of A. glandulosa and A. glauca. Possibly hybridization with A. glandulosa at the edge of the A. rainbowensis range.
Perennial evergreen shrub . Burl-forming and vigorous at resprouting .
Bloom period is December-March .
Produces large amount of fruits and readily establishes seedlings on sites disturbed by bulldozers or wildfires .
Development and agricultural conversion .
Flowers and fruits are often heavily infested with boring insects on the eastern edge of its range . A. rainbowensis is the only Arctostaphylos species throughout most of its range.
 Parker, V. T., M. C. Vasey, and J. E. Keeley 2016. Arctostaphylos rainbowensis, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=76574, accessed on September 07, 2016
 CNPS, Rare Plant Program. 2016. Inventory of Rare and Endangered Plants (online edition, v8-02). California Native Plant Society, Sacramento, CA. http://www.rareplants.cnps.org, accessed 07 September 2016.
 Keeley, J. E., and A. Massihi. 1994. “Arctostaphylos Rainbowensis, a New Burl-Forming Manzanita from Northern San Diego County, California.” Madroño. Los Angeles, CA.