What is an herbarium?

Pressed and living samples of
Nepenthes burbidigeae


By Michael Chamberland

An herbarium is a repository of preserved and labeled plant specimens, arranged to allow easy access and archival storage. The specimens are typically in the form of herbarium sheets: pressed and dried plants that have been glued or sewn to a sheet of heavy paper together with a data label. The label describes useful information including the plant's Latin name, the origin of the collection, the date of collection, and the name of the collector. Herbarium sheets are all of standardized size and arrangement, and are filed in protective storage cabinets. Within these cabinets the specimens are arranged according to the family, genus, and species they represent, as well as the geographic location from which they were collected.

Our Mission: The mission of an herbarium is to preserve and document the diversity of plants - from duckweed to sequoias. This mission to preserve all forms of plant life may be complicated by those that are too large or bulky to press and fit on a standard herbarium sheet. Cacti, palms, and rock-growing lichens present such challenges. In some cases a specimen may be spread out on several separate sheets. Large structures like pine cones may be stored in separate boxes. Delicate organs such as orchid flowers may be pickled and stored in jars. Specimens may also be complemented by photographs added to the sheet.

Other Collections: Many herbaria also preserve specimens of fungi, lichens, and even some bacteria (plant pathogens and cyanobacteria) in their collections. These organisms are not plants, but historically these "plant-like" organisms or structures (such as the fleshy fruiting bodies of fungi) were regarded as plants. Since these specimens may be preserved in much the same way as plants, their place in herbaria has been maintained. However, no herbaria attempt to fully represent the diverse kingdoms of Fungi or Monera.

Cladonia cristatella

An Herbarium Specimen: An herbarium specimen is simple in form and low-tech in preparation, yet it preserves a wealth of valuable information. If properly stored, an herbarium specimen will last for centuries without much deterioration. Specimens document the variation in form and geographical range of species. Specimens preserve short-lived structures like cactus fruits, and rarely produced organs such as bamboo flowers. Herbaria also document valuable historical collections, such as "type specimens", the original specimens on which a plant's Latin name is based. The data label preserves valuable information about plant habitats. Many herbarium specimens record the existence of plants in habitats now developed and lost. They may also record the spread of weeds and new introductions like the European Helleborine orchid in Michigan. Some herbaria house the last preserved material of extinct plant species, such as the bizarre Thismia americana, once found in wet prairies near Chicago.


Research: Herbarium specimens are very useful tools for botanists, particularly taxonomists, who seek to describe plant species, their form, and their habitats. Herbaria located at different institutions regularly loan specimens to each other to aid investigators working on specific groups of plants. Herbarium specimens are also useful for teaching purposes, since live material is not always available.


Other Equipment: In addition to plant specimens, herbaria regularly contain microscopes, plant presses, specimen dryers, and other tools for collecting, preserving and examining plant material. Herbaria often possess a library of books, journals, and maps useful for plant identification and taxonomic study.

An Herbarium Compactor

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