The combined Herbarium of Rancho Santa Ana Botanic Garden (RSA) and Pomona College (POM) is a museum-quality collection of vascular plant and bryophyte specimens. With current holdings totaling over 1,250,000 specimens, the Herbarium is the third largest in California. The Herbarium is recognized throughout the world for its strength in documenting the diversity, distribution, variation, and ecology of more than 6,500 species of flowering plants, conifers, and ferns in California, which constitutes nearly 50% of the total collection.