RSA-POM Herbarium

Overview    Herbarium staff 1

The combined Herbarium of Rancho Santa Ana Botanic Garden and Pomona College (RSA-POM) is a museum-quality collection of vascular plant specimens. With current holdings totaling over 1,200,000 specimens, the Herbarium is the tenth largest in the United States and 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 6500 species of flowering plants, conifers, and ferns in California, which constitutes nearly 50% of the total collection. The holdings from Southern California exceed 250,000 and are unsurpassed by any other herbarium. In recognition of its overall strength, RSA-POM has been designated a national Research Resource Collection.

Approximately 95% of the collection is composed of mounted sheets and filed according to a standardized system of classification. Ancillary collections that augment the collection include a cone & fruit collection, wood collection, fluid preserved collection, and pollen and anatomy slide collection.

The RSA-POM Herbarium is an active member of the Consortium of California Herbaria

Contact Information

This email address is being protected from spambots. You need JavaScript enabled to view it., Collections Manager

Visiting the Herbarium

The RSA-POM Herbarium is open to the public Monday through Friday, 9:00 AM – 5:00 PM. Special arrangement can be made with Herbarium staff if necessary. Visitors are advised to arrange use of the herbarium by contacting the Collections Manager in advance of visiting. If you are a first time visitor, please review the collections policy and protocols for handling herbarium specimens. Please be aware that destructive sampling requires prior permission.

Upon arrival, please check in at the front desk of the Administration Building in the Garden Gift Shop.


Total holdings: Over 1,200,000 specimens

Type specimensApproximately 7,000 specimens

Ancillary collections: cone & fruit collection (3,000 specimens); wood collection (8,000 specimens), fluid preserved collection (3,500 specimens); pollen and anatomy slide collection (approximately 30,000 slides)

Systematic arrangement: Specimens in the collection are arranged by larger taxonomic groupings: Psilotopsida, Lycopsida, Sphenopsida, Filicopsida, Gymnospermae, Angiospermae (Moncotyledons, “Dicotyledons”). Within each of these units families are arranged in alphabetical order.

Geographic arrangement: Within each genus, the collection is organized by geographic region.

Specialties: California, southwestern U.S., Mexico (with emphasis on Baja California), Australia and other arid regions.

Other specialties include: Russia and former U.S.S.R. republics; Australasia and other Pacific; Cactaceae; Crossosomataceae; Goodeniaceae; Midaceae; Poaceae; Polemoniaceae; Restionaceae; Stylidiaceae; Arctostaphylos; Astragalus; Camissonia; Ceanothus, Cupressus; Iris; Ranunculus; aquatic phanerogams

Important collections include: C. F. Baker, R. C. Barneby, L. Benson, S. Boyd, S. Carlquist, A. Davidson, C. Davidson, P. H. Davis, M. DeDecker, M. B. Dunkle, F. R. Fosberg, H. S. Gentry, V. Grant, R. Gustafson, G. B. Hinton, E. C. Jaeger, M. E. Jones, C. L. Lundell, Y. E. J. Mexia, P. A. Munz, E. Palmer, F. W. Peirson, C. G. Pringle, P. H. Raven, J. C. Roos, T. S. Ross, A. C. Sanders, R. F. Thorne, L. C. Wheeler, and C. B. Wolf.


Nearly 500,000 (~42%) of the >1.2 million herbarium specimens held by RSA-POM have been databased, which includes all of our California holdings as well as many specimen records in North America and worldwide. The majority of these specimen records are available through the RSA-POM web portal and more will become available as new records are uploaded.

All California specimen records are also available through the Consortium of California Herbaria portal.


Engaging our future to preserve our past: curation and preservation of historically significant collections through student participation

Natural history specimen collections offer a lens into the past and a means to envision the future. Collections are especially important in predicting biodiversity change with shifts in climate and land use. The RSA-POM Herbarium recently received NSF funding to process, curate, and digitize 30,000 plant specimens collected by ten significant botanists of the 20th century. Seventy percent of these were collected from 15 of 34 designated world biodiversity hotspots; thirty percent represents the California Floristic Province biodiversity hotspot alone. Several specimens have been identified as valuable type material (i.e., specimens used to describe and name species new to science). Curation of these collections will provide physical access to collections currently unavailable for study, promote discovery of species new to science, and yield new distribution and phenology data. Importantly, curation will ensure critically needed preservation. Digitization efforts will provide access of this rich source of specimen data to researchers, students, and the public. Integral to the project are activities involving participation from graduate students, undergraduates, and high school students. Notably, the Herbarium will expand on a successful undergraduate internship program by engaging underserved youth from the Greater Los Angeles metropolitan area. Especially targeted are at-risk and transitional aged youth at the high school level, who will be trained in a six-week summer junior intern program. All interns will participate in five workshops that will serve to connect students to collections, natural history, and biodiversity. An exhibit at RSABG will highlight the activities and student participation in the project.

Progress on this project can be found here. 


Harnessing the power of herbaria to understand the changing flora of California: A biodiversity hotspot in peril

This project, supported through an NSF grant, is a collaborative endeavor among more than 21 institutions that are part of the Consortium of California Herbaria to database ~400,000 specimens of California plants and to georeference >500,000 specimens. The flora of California is one of the most imperiled on Earth and, with climate change added to the perils, vouchered specimen data are invaluable to predict, monitor and understand the effects of climate change on the state’s plants. At RSA-POM, we have responsibility for both data entry and georeferencing, as well as oversight of the work of six other participants (UC Riverside, Cal State San Bernardino, San Diego Natural History Museum, Santa Barbara Botanic Garden, UC Los Angeles, Cal State Sacramento). RSA-POM’s commitment was to database and georeference 72,384 and 107,189 specimen records, respectively. The databasing of all of our California holdings was completed in Augsut 2014, with 426,744 specimens databased. As of November 2015, 149,411 records have been geo-referenced, of which 88,044 records were target taxa (rare, threatened, endangered, alpine taxa, or ecological dominants including woody plants and grasses). A recent supplement has enabled the RSA-POM Herbarium with several other Consortium institutions to add ~20,000 records of rare, threatened, endangered, and endemic taxa of the California Floristic Province (CFP) in Baja California.


Digitizing the collections and archives of Marcus E. Jones

Marcus E. Jones (1852–1934), geologist, mining engineer, and self-trained botanist, became one of the most prominent botanists of the American West. Most active during the late 19th century into the early part of the 20th century, Jones traveled extensively throughout the western United States and Mexico, collecting thousands of plants, and photographing and recording detailed notes of the regions he traveled in. Jones’ plant collecting at the turn the turn of the century provided an early comprehensive characterization of the flora of the West; he collected in areas that were poorly known, some of which have since been developed. Jones also described hundreds of new species, many of which are represented as type specimens. Jones’ influence on botany is great, and his works and supporting materials (i.e., specimens and archives) are continually sought. Rancho Santa Ana Botanic Garden (RSABG), the locus of Jones’ archives and plant specimens, receives frequent requests to view and study Jones’ photographic slides, notebooks, and plant specimens.

Rancho Santa Ana Botanic Garden has received support from The Andrew W. Mellon Foundation to digitize and make available the most botanically and historically significant components of the archives and collections of Marcus E. Jones. Prioritization of the project focuses on the archives and plant collections associated with several trips that Jones made to Mexico (1892, four trips during 1926–1930) and Baja (1882), and collecting notebooks and other written materials from field trips that emphasize plants or collecting.

Following the established protocols of the Global Plants Initiative, we have databased, barcoded, and digitized more than 3000 herbarium specimens from Jones’ 1892 and 1926-1930 trips to Mexico and 1882 trip to Baja California. At present we are databasing and imaging his collections from western North America (excluding CA), and thus far have digitized >5000 of these collections.


Collections Policy

Loan Policy

Destructive Sampling

Handling Herbarium Specimens

Specimens for Deposit

Template for Botanists


As a non-profit institution that promotes botany, conservation, research, and education, an important part of the mission of Rancho Santa Ana Botanic Garden is to serve the public. 

In keeping with this mission, the Rancho Santa Ana Botanic Garden Herbarium provides plant identification services. Plant identifications include determination of plant name, geographic distribution, and if necessary, library research. A number of factors influence our ability to provide an accurate and timely identification. A complete specimen prepared according to our specifications will be more likely to include the characteristics necessary for an efficient identification. The main focus of our specimen collection and taxonomic literature is the native and naturalized flora of California and Mexico. We are most likely to be successful in providing identifications for plants from this region. In general, we do not identify cultivated plants, which can come from anywhere in the world. In some cases, however, we may be able to assist you if the cultivated plant is also native to our focal region.

Plant identification fees

•  Plant identifications are free of charge to researchers from non-profit and public sector institutions, government organizations at all levels, and the general public.

•  For for-profit organizations that wish to use our services, fees are determined on an hourly basis, with a 1-hour minimum charge of $50. Fees charged for plant identification services are used to improve the Herbarium and its ability to serve the public.

Specimen preparation

Please download and follow the specimen preparation instructions and submit this identification request form.


To reach the herbarium please call (909) 625-8767, ext. 244.

Staff with direct extensions are listed below.

Mare Nazaire, Herbarium Collections Manager, (909) 625-8767, ext. 268

LeRoy Gross, Senior Curatorial Assistant, (909) 625-8767, ext. 264 

Rachel Poutasse, Herbarium Workroom Manager, (909) 625-8767 ext. 233

Joy England, Curatorial Assistant II, (909) 625-8767, ext. 242

Jill AzzoliniProject Manager, (909) 625-8767, ext. 244

Curatorial Assistant I

Grace Rice

Sierra Sutton

Lauren Tucker

For volunteer and internship opportunities, please inquire with the Herbarium Collections Manager.