Based on herbarium fragments, a preliminary determination has been made that <i>Rosa adenocarpa</i> Greene is a possible synonym of <i>R. spithamea</i> S. Watson.

See the annotations to New York Botanical Garden Virtual Herbarium specimens of <i>Rosa adenocarpa</i> Greene and the comments by Barbara Ertter on her website, Native California Roses at http://ucjeps.berkeley.edu/ina/roses/rosa_spithamea.html.