Published on March 31, 2015 10:35 am MT
Updated on February 6, 2020 8:14 am MT


The Charles Maurer Herbarium Collection at Colorado State University (CS) is the third largest collection of plants and the oldest herbarium in the southern Rocky Mountain region and has an excellent representation of the Colorado Flora. It serves as a regional center for plant systematic research and receives about four hundred visitors per year. The Charles Maurer Herbarium Collection contains approximately 100,000 specimens of vascular plants, primarily from Colorado. It is from this collection that Harold D. Harrington, one of the former curators, compiled his well known Manual Of The Plants Of Colorado, published in 1954.

The herbarium also has a large collection of plant identification keys from Colorado and other areas, and an extensive collection of reprints on floristics and systematics. Patrons are welcome to use any of these resources while visiting the herbarium.  An especially valuable resource available to researchers is the herbarium’s database of 100,000 herbarium specimens, housed through SEINet.  We have also successfully digitized the entire herbarium, and images of specimens are available for searching as well.

The herbarium is free and open to all patrons, and is broadly used by members of the university including numerous students, state and federal agencies, and the general public for plant identification. In addition to students, approximately 300 visitors come to the Charles Maurer Herbarium Collection each year, seeking help identifying plants, investigating regional floristic diversity, studying specimens for preservation of rare or endangered species, and preparing systematic monographs.

The herbarium houses specimens deposited by, or belonging to, The Nature Conservancy, The Rocky Mountain Heritage Program, The Colorado Natural Heritage Program, The National Park Service and the Charles Maurer Herbarium Collection.


The Charles Maurer Herbarium Collection at Colorado State University is recognized internationally through listing by the International Organization of Plant Taxonomy (Index Herbariorum, Edition 8), which identifies and serves as a directory of the major research herbaria throughout the world. In 1974, the herbarium was designated a Natural Resource Collection by a committee of the National Science Foundation (Systematic Botany Resources in America, Part 1. New York Botanical Garden, 1974). Such collections, numbering about 105 throughout the U.S., were designated on the basis of scientific significance, representation of a particular area, and professional activity of associated staff members.

Important collections include those by J. Cassidy, J. H. Cowen, C.S. Crandall, and H.D. Harrington. The Charles Maurer Herbarium Collection has an excellent representation of the Colorado flora as well as the flora of the southern Rocky Mountain region. The well known Manual of the Plant of Colorado by Harrington (1954) was based primarily on this collection.

Acquisition of Species

The Charles Maurer Herbarium Collection is a depository for voucher specimens from research projects of the faculty, staff, and graduate students at Colorado State University. It has been a major depository (with the University of Colorado Museum) of collections made by the Colorado Natural Heritage Program, the Nature Conservancy, the Colorado Natural Areas Program, and the National Parks Service units in Colorado. Specimens with high quality can be deposited at CS from other researchers, investigators, and private collectors.

The focus of Charles Maurer Herbarium Collection is the Colorado flora.  Voucher specimens collected outside Colorado through research projects by CSU faculty, staff, and graduate students are generally accepted if the collections meet the quality requirement. Plant specimens collected from the Southern Rockies by other organizations can be accepted upon the approval from the Curator.

In order to be acceptable for accession, specimens must meet the following criteria:

  • Specimens must be of identifiable quality
  • Specimens should have enough material to spread on a herbarium sheet; and herbaceous plants should generally bear roots, stems, leaves, and reproductive organs.
  • The specimens should be well labeled and include complete collection data.
  • The nature of the specimens must be consistent with the goals of the herbarium (Collections).
  • Specimens collected without appropriate permits are not accepted.


The collections of the Charles Maurer Herbarium Collection at Colorado State University are available for study by all qualified investigators. All requests of loans should be addressed to the curator. The herbarium only loans its material to institutions, not to individuals. Loans are made generally for 12 months. Extensions of the loan period may be granted upon request to the curator. Transfers of loans may be made with the permission of the curator.

The Charles Maurer Herbarium Collection requires the returning loan be packed carefully to avoid damaging the specimens. The herbarium expects the investigator to annotate each sheet of the loan with annotation labels and acknowledge CS in any publications resulting from using the CS collections. Reprints of any publications are requested.

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