Northern Ontario Plant Database

What is an Herbarium?

An herbarium (pronounced with a silent 'h') is a collection of pressed and dried plant specimens mounted on sturdy paper. Each sheet, with the attached plant, is referred to as an herbarium specimen. Information, such as the name of the specimen, where it was collected, who collected it, and when it was collected is recorded on the herbarium label, which is usually mounted in the lower right-hand corner of the sheet. Herbarium specimens are arranged in folders according to their plant family and stored in an herbarium cabinet. Standard metal herbarium cabinets, like those found at the Claude Garton and Great Lakes Forestry Centre Herbaria, are 2.0 m tall × 0.75 m wide and divided into 2 columns of 12 rows. Depending upon the number of specimens in a collection, other sizes or types of herbarium cabinets many be used.

When each plant species is assigned a scientific name, a detailed description of the plant, in both Latin and English is published, along with reference to one or more herbarium specimens that clearly represent, or typify, the species being described. These designated specimens are called Type Specimens, and each serves as an official record of the physical appearance of a particular species. Comparing an herbarium to a dictionary, each herbarium specimen would be analogous to the definition of one word. If there is confusion about the identity of a species, botanists (scientists who study plants) can refer to the type specimen for clarification of the physical appearance of the species. Most type specimens are housed in the herbaria of major universities; no type specimens are included in the partner collections.

Herbarium specimens are often used to verify the identity of another specimen. To identify an unknown plant, a local field guide or technical reference is usually consulted. Based on the available descriptions and/or illustrations, a species name is determined. Sometimes, it is necessary to compare your specimen to known specimens in the herbarium, particularly if a number of species are similar in appearance.

Herbarium specimens are also official records of the geographic location of a species. Specimens collected to document the occurrence of a species a at a given research or study site are called voucher specimens. These serve as proof that the species actually did occur at the sites. If there is confusion about the identity of the species recorded for a site, the voucher specimen can be checked for accuracy. Distribution maps for each species can be constructed by plotting the location given on each herbarium sheet on a base map.

For further information on herbaria and how they work, visit the University of Iowa Herbarium website.