An herbarium is a collection of pressed, dried plant specimens
that are mounted on archival paper. These specimens, which are typically housed
in metal storage cabinets are often arranged in alphabetical order by family,
genus and species.
Functions of an Herbarium
1) Providing a standard reference collection for verifying
the identification of newly collected plants. This is a major function of
many small herbaria.
2) Serving as a reference collection for plant systematics and other botany courses.
3) Training graduate and undergraduate students in herbarium practices.
4) Documenting the presence of a species at particular locations and providing data on its geographic range. It is often possible to go back to the exact spot where a plant was originally collected and to find again the plant material.
5) Providing samples of the flora of an area. For example, it is possible for an ecologist to go to the herbarium and put together a series of specimens that represent the major vegetational components of a region. By studying these specimens, much time may be saved while in the field. Also, a systematist writing the flora of a region would go through the herbarium to ascertain which species are represented in the flora.
6) Pointing out the existence of classification problems. A preliminary examination of herbarium specimens may indicate that a species contains plants that do not combine the characters normally listed in manuals, therefore suggesting the need for additional studies.
7) Providing plant material and data for analysis. Data are available in the form of vegetative and reproductive morphology; pollen samples; leaf samples for chemical analysis; anatomical samples; data for distribution maps; and ecological, economic, and ethnobotanical data from the labels.
8) Preserving type specimens and serving as a repository of chromosome, experimental, and chemosystematic vouchers. Looking at type material allows a researcher to determine which plant was described by the original author and to find the exact specimen associated with the name. Modern systematic literature is documented by reference to individual plant specimens according to herbarium, collector, and collection number.