Natural distribution map for <i><b><a href="//commons.wikimedia.org/wiki/Category:Cupressus_forbesii" title="Category:Cupressus forbesii">Cupressus forbesii</a></b></i> (green, in southern California and Baja California) — and <i><b><a href="//commons.wikimedia.org/wiki/Category:Cupressus_guadalupensis" title="Category:Cupressus guadalupensis">Cupressus guadalupensis</a></b></i> (red, on Guadalupe island only).
Elbert L. Little, Jr., of the U.S. Department of Agriculture, Forest Service, and others
1971
<a rel="nofollow" class="external text" href="https://esp.cr.usgs.gov/data/little/">USGS Geosciences and Environmental Change Science Center: Digital Representations of Tree Species Range Maps from "Atlas of United States Trees" by Elbert L. Little, Jr. (and other publications)</a>, population data points from <a rel="nofollow" class="external text" href="http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0016133">Rosas Escobar P, Gernandt DS, Piñero D, Garcillán PP (2011) Plastid DNA Diversity Is Higher in the Island Endemic Guadalupe Cypress than in the Continental Tecate Cypress. PLoS ONE 6(1): e16133. doi:10.1371/journal.pone.0016133</a>