Skip to Main Content
Idaho State University home

The Ray J. Davis Herbarium

The Ray J. Davis Herbarium (IDS) is a historically, regionally and nationally important collection of over 70,000 plant and lichen specimens, including 137 type specimens. The collection well represents the plant diversity of Idaho as well as providing reference material of North American and global plant families. Plant specimens from the U.S. make up 96% of the collection, with 70% from Idaho and surrounding states. Idaho specimens make up 48% of the collection, with Southeast Idaho especially well represented (32% of total specimens, 66% of Idaho specimens). Southeast Idaho is a geographically and biotically diverse region that includes the western extent of the Greater Yellowstone Ecosystem and the volcanic landscapes of the Upper Snake River Plain. IDS contains one of the largest collections of Southeast Idaho plants (22,409 specimens), and is thus one of the most important sources of information on the historical distributions of the regions’ plants and a growing resource for future research in this era of changing climate and landscape use. IDS receives frequent use for research, education and outreach. The plant and lichen collections are completely digitized and searchable via The Consortium of Pacific Northwest Herbaria (, the Consortium of North American Lichen Herbaria (, and the NSF-sponsored Integrated Digitized Biocollections Hub (

The herbarium was established by Dr. Ray J. Davis in 1931. Davis recognized the need for a regional flora and spent the next 20 years collecting plants throughout Idaho, and maintaining active loan and exchange programs with the leading botanists of the region, to document Idaho’s plant distributions and diversity. This effort built the collection to about 35,000 specimens and culminated in the publication of The Flora of Idaho (1952). Davis retired in 1965 and was succeeded by Dr. Karl E. Holte. For over 30 years Dr. Holte and his students conducted numerous biotic surveys in the region and grew the collection to ca. 50,000 specimens. In 2008, Dr. C.F. Rick Williams was appointed curator. The vascular plant collection has since grown significantly (ca. 2000 specimens per year) from processing and accessioning of vouchers from historical and contemporary biotic surveys. These collections are a rich source of information on the floral diversity and phenology of Southeastern Idaho dating from the 1930s to present.


As part of the digitization project (SWITCH) a searchable online database is hosted by the Pacific Northwest portal at the University of Washington. Records from the Ray J. Davis Herbarium are identified with the prefix IDS loans of those collections should be directed to the director of Ray J. Davis Herbarium.


Intermountain Regional Herbarium Network

Idaho Native Plant Society


The work at the herbarium could not be completed without the contribution of numerous volunteers over the years. Students and members of the community have donated

collections, mounted specimens, entered information into the database imaged specimens and filed collections.

Volunteering for its own sake may be enough reward for some people, but seeing numerous plant collections is a great way to learn plant names and how the plants are
classified into families. Many of our volunteers have commented that their experience in the Herbarium was a deciding factor when they successfully applied for plant related