The tenth largest herbarium in the United States

The combined Herbarium of Rancho Santa Ana Botanic Garden and Pomona College ("RSA-POM") is the tenth largest in the U.S. and the third largest in the western U.S., with current holdings totaling over 1,100,000 specimens.

Approximately 95 percent of the collection is composed of mounted sheets which are housed in four rooms (wings) within the Plant Science Center Building. The RSABG's herbarium is recognized throughout the world for its strength in plants of California, which constitute nearly 50 percent of the total collection. The holdings from Southern California exceed 250,000 and are unsurpassed by any other herbarium. Active collecting over many decades means that the specimens are well distributed through time as well as in their geographic origin. In recognition of its overall strength, RSA-POM has been designated a national Research Resource Collection.

The RSA-POM herbarium is an active member of the Consortium of California Herbaria. Unpaid internships are available in the herbarium throughout the year. 

Please contact the Herbarium staff at (909) 625-8767, ext. 244 or email This e-mail address is being protected from spambots. You need JavaScript enabled to view it .