The Herbarium

The Herbarium at the University of California, Riverside (UCR) serves as an important source of information for the Southern California regional community as well as for botanists from around the world. UCR specimens and records are used by academic researchers, biological consulting firms, farmers and other individuals involved with plants as a business, research topic, management concern, or just a personal interest. One hundred percent of UCR specimens are databased and 93% are georeferenced (mappable in geographic information systems). Currently UCR is the 4th largest contributor to the Consortium of California Herbaria (c. 171,500 specimens contributed). UCR's oldest specimen was taken September 1859 on the Hayden Expedition, Powder River, Wyoming, but most are much more recent (e.g., >4,800 collected after 2015). The UCR Herbarium documents the abundance and distribution of species, including changes in range over time and the arrival of invasive species, the rediscovery of "extinct" species, and the collapse of native plant populations regionally.

The UCR herbarium currently (Jan. 2018) houses over 273,000 vascular plant specimens. Of these, c. 229,500 are from the United States, of which c. 190,200 are from California. Mexico is represented by c. 38,300 specimens. The rest of the specimens are miscellaneous collections from other areas of the Western Hemisphere from Alaska to Tierra del Fuego. UCR is a general collection, but with particularly strong holdings of Juniperus, Triticeae (B. L. Johnson & J. G. Waines collection of Triticum and relatives), and Phaseolus. It is one of the strongest herbaria for the flora of Southern California and is also very strong on the flora of western Mexico. A detailed overview of the collection is available on our summary web page.

The lichen collection currently (January, 2018) contains 16,000 specimens, 13,600 of which are from California. Important lichen collectors represented at UCR include Kerry Knudsen, H. E. Hasse, F.M. Reed, Jana Kocourková, James C. Lendemer, T.H. Nash and Rick Riefner, Jr. The collection is strong in Acarosporaceae and lichenicolous fungi.

UCR houses a collection of unusually high quality specimens, there are few scrappy specimens or specimens with scant label data. Almost all of our specimens have latitude/longitude data, and the rest will have coordinates soon. Many of our collections were generated locally in relatively recent times and so provide one of the best current pictures of the flora of southern California. Our collection from western Mexico is also unusually strong and in many cases is not duplicated elsewhere.

The UCR Herbarium is heavily used by the general community in southern California. Most visitors are people who bring in plants for identification, but others are researchers coming from southern California, and other parts of the world, to study the collection. Also important are the volunteers who contribute their time and brains to the operation of the herbarium.

The UCR herbarium is one of the most active in California in making identifications for the public and for other researchers. Every year we make 5-10 thousand identifications for individuals not affiliated with the herbarium, and c. 1/4 of the plants identified are made into specimens. In addition we have an active collection program which generates thousands of additional specimens every year. As a result of the massive flux of material resulting from these two sources we are one of the more active herbaria in specimen exchange: we send out many thousands of specimens to c. 25 other herbaria. In many cases we are among the other herbaria's most active exchange partners and, even in the case of some very large herbaria (e.g., Rancho Santa Ana in Claremont, California), we are in many years their major exchange partner in numbers of specimens sent. The UCR Herbarium also actively helps researchers unable to come to Riverside to look at specimens in the inventory by loaning them specimens through their local herbarium. Loans averaged 10 to 15 per year.


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