The Ada Hayden Herbarium, housing over 640,000 specimens, including the recently transferred University of Iowa Herbarium (IA), ranks within the top 12 in size among university herbaria in the United States. It is also within the top 20 in size of more than 600 United States herbaria, including those at botanical gardens and museums.
The herbarium's general collection contains the largest number of specimens. The general collection includes flowering plants (angiosperms), conifers (gymnosperms), ferns (pteridophytes), mosses and liverworts (bryophytes), algae and lichens, Iowa's vascular plants, grasses from throughout the Western Hemisphere, and legumes from North America.
Representatives of virtually all of Iowa's estimated 2000 species of ferns, conifers, and flowering plants are included in the herbarium. These holdings are the fundamental reference for such works as The Vascular Plants of Iowa (L.J. Eilers and D.M. Roosa, 1994), Distribution of Iowa's Threatened and Endangered Vascular Plants (Iowa Department of Natural Resources, 1988, and unpublished revision, 1994), and Flora of North America (N.R. Morin, editor, ongoing series).
The herbarium's large holdings of grasses of the Western Hemisphere comprise one of the premier university collections of grasses in the United States. The special interest in grasses at Iowa State University began with Louis H. Pammel, was enhanced greatly by the long tenure of Richard W. Pohl, and continues with the work of Lynn G. Clark.
Holdings Received from IA
Approximately 220,000 accessioned specimens of vascular plants and bryophytes were received through the transfer of the University of Iowa Herbarium (IA) in 2004 to ISC. The vascular plants comprise about 165,000 specimens and the bryophytes about 55,000 specimens. The vascular plants include over 75,000 Iowa collections with strong representation from the eastern third of the state and other regions of the state surveyed during Robert Thorne's tenure. The IA bryophyte collection is regionally and historically significant and ranked 12th nationally as of the early 1990's, according to Dr. Diana Horton, the former curator of IA. In addition to the representation of Iowa bryophytes (about 30% of the total), the collection includes strong holdings of Upper Midwest bryophytes and good representation of North American diversity generally (about 60% of the total). The remaining 10% are specimens from countries outside of North America. About half of the IA bryophyte holdings are Conard specimens and another significant number are those of Shimek, Drexler and Hulbary.
The numerous classical taxonomic studies that have been associated with the Ada Hayden Herbarium have resulted in the accumulation of over 2000 type specimens. In particular, the studies of grasses and legumes have produced significant numbers of types that are housed here. The Parry Historical Collection and the addition of the University of Iowa fungal holdings have also added many type specimens.
C. C. Parry Historical Collection
Charles Christopher Parry, a resident of Davenport, Iowa, collected thousands of plant specimens throughout the midwestern, western and southwestern United States, and northern Mexico. He also actively exchanged specimens with other preeminent botanists of the period. The holdings in this set were all collected between about 1848 and 1895. Often these are the earliest known collection from an area and thus are of great historical interest. The Parry collection also contains many type specimens.
J. P. Anderson Alaskan Collection (now at ALA)
Through the efforts and support of Jacob Peter Anderson, the herbarium housed one of the world's largest collections of Alaskan plants, based on his 11,000 personal collections and thousands of additional specimens he had accumulated by gift and exchange. Anderson began work in 1941 on an Alaskan Flora. Richard Pohl compiled Dr. Anderson's series of treatments into a single volume Flora of Alaska, published in 1959. A bequest left to the College by Dr. Anderson allowed for additional field work in Alaska and northwestern Canada and for a revision of Anderson's Flora by Dr. Stanley Welsh. The updated treatment by Welsh, published in 1974, is titled Anderson's Flora of Alaska and Adjacent Parts of Canada. As of 2003, the J.P. Anderson Alaskan Collection included approximately 30,000 specimens. In late 2003, this collection was transferred on permanent loan to the Herbarium (ALA) of the University of Alaska Museum at the University of Alaska, Fairbanks.
Mycological (Fungus) Collection
Charles Bessey, the founder of the herbarium, added approximately 1500 fungal specimens to the herbarium's holdings. Bessey's first student was J. C. Arthur, who eventually became the leading authority on the rust fungi. His early work on fungi increased the holdings of the herbarium. L. H. Pammel and his students, including George W. Carver, continued to build the mycological collection. Pammel himself added approximately 7,500 specimens. In 1916, Irving E. Melhus was hired as Iowa State's first plant pathologist. Two years later, Joseph C. Hilman joined Melhus as a mycologist and plant pathologist. Subsequent studies of plant diseases, continuing today through the work of Lois H. Tiffany, have added numerous specimens. Dr. Tiffany is also responsible for the placement here of the prestigious University of Iowa Mycological Herbarium when it was decided that the collection could no longer be housed at Iowa City. This collection contains the specimens of George Martin, Thomas H. Macbride, and A. P. Morgan, and is rich in type specimens. Currently the mycological collection contains an estimated 25,000 packeted and boxed specimens and numerous bound exsiccatae.