The California Botanic Garden hosts the third-largest
herbarium in the state (10th largest in the US), which is home to over 1,200,000 specimens. The herbarium is a combination of the Rancho Santa Ana Botanic Garden and
Pomona College herbaria (RSA-POM). It hosts the largest collection of Southern California plants in the world, totaling over 250,000 specimens. Most of the collection, around 95%, is composed of pressed
vascular plants mounted on sheets. The ancillary collections of the herbarium consist of cone and fruit collections, wood collection, fluid-preserved collections, and pollen and anatomy slide collection. The herbarium also has a modest
bryophyte collection. The RSA-POM herbarium is an active member of the Consortium of California Herbaria. The herbaria of Pomona College (POM) and Rancho Santa Ana Botanic Garden (RSA) have long been in association, being housed together since the Garden’s relocation in 1951 and fully integrated in the late 1960s. Management of the separate collections was consolidated in the mid-1970s, but they were under separate ownership until the 1st of June 1996, when formal ownership of the Pomona College Herbarium was transferred to California Botanic Garden. The specimens acquired from Pomona College kept their POM accession identification for historic continuity. Since then, all new collections to the Garden have been accessioned under RSA. After the name change to California Botanic Garden, the herbarium still retains its RSA accession identification for historical continuity. The Garden also houses herbarium collections from various other institutions, such as the
Natural History Museum of Los Angeles County, the
University of Southern California, and the Alan Hancock Foundation, which have changed accession identity to be under RSA or POM. ==See also==