What is a herbarium?

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A herbarium is a collection of preserved plant or fungal specimens. Many Herbaria were established throughout Europe in the 1600s, during the age of exploration when botanical gardens could no longer keep living collections of all the known species and thus preserving and storing specimens became common practice.

The largest herbarium in the world is ​at the National Natural History Museum in Paris, France, with over 9.5 million specimens. The largest herbarium in the United States is the New York Botanic Gardens Herbarium, established 1891, with over 7 million specimens.

Many Herbaria in the USA were established throughout the 1800s. The USA has 405 registered herbaria with a total of 59 million specimens or 22% of the world's herbarium collections.

Herbarium specimens include plants, conifers, ferns, mosses, liverworts and algae as well as fungi and lichens. Most plant specimens are dried by pressing whereas bulkier plants and most fungi are dried without pressing and are stored in boxes.

Pressed specimens can be mounted on archival sheets or stored in packets, as in the case for most of the material in the Arthur Fungarium, for example.

Additional names can be used for more specialized collections, for example:​

  • A collection of fungi is a Fungarium.
  • A collection of plants is a Herbarium.
  • A collection of wood specimens is a Xylarium.
  • A collection of cultivated plants is a Hortorium.

What is a type specimen?

According to a precise set of rules laid down by the International Code of Nomenclature for algae, fungi and plants (ICN), the scientific name of every taxon is almost always based on one particular specimen. This is usually a physical specimen that must be accessioned in a museum or herbarium research collection.

Types are of great significance. When identifying material, a researcher attempts to apply a taxon name to a specimen or group of specimens and this will be based on their understanding of the relevant taxa, using (at least) the type description, but preferably based on an examination of all the type material of all of the relevant taxa. If the taxon appears not to have been named, then the scientist or another expert designates a type specimen and publishes a new name and an official description.

This process is crucial to the science of biological taxonomy and biology as a whole and these type collections are considered the lynchpin of biological research.

Types of types

There are actually several types of types. Here are the definitions of some common types:

  • Holotype: When a single specimen is clearly designated in the original description, this specimen is known as the holotype of that species.​
  • Isotype: Any duplicate specimen of the holotype.
  • Lectotype: Designated as the type when no holotype was identified by the original author, or when the holotype is lost or destroyed. It is chosen from among the specimens available to the original publishing author.
  • Syntype: Any of two or more specimens listed in the original description of a taxon when a holotype was not designated.
  • Isosyntype: A duplicate of a syntype.
  • Paratype: A specimen not formally designated as a type but cited along with the type collection in the original description of a taxon.
  • Neotype: A specimen chosen by a later researcher to serve in place of a holotype when all specimens available to the original publishing author of a scientific name have been lost or destroyed.
  • Topotype: A specimen of a plant collected from the same locality as the holotype and usually on a different date. A topotype has no formal standing.
  • Cotype: A term formerly used for syntype and sometimes (erroneously) for isotype and paratype. This is an old term that was used loosely and is not used by today's taxonomists.​

What can you do with a herbarium collection?

Basic functions and Research

  • Facilitate the discovery or confirmation of new species and provides ecological and range data for existing species;
  • Voucher scientific research;
  • Repository for type specimens;
  • Provide information on rare or extinct species;
  • Material for morphological studies and documentation of flowering, and fruiting times;
  • Species locality data;
  • Provide data for agriculture, human health, biosecurity, forensics, control of invasive species, conservation biology, natural resources, and land management;
  • DNA analysis​ and sequencing. (For example, using herbarium specimens of potato and tomato leaves infected with Phytophthora infestans for the first time scientists have decoded the genome of a plant pathogen and its plant host from dried herbarium samples);
  • Document specialist’s concepts;
  • Provide information on predators, pathogens and symbionts that may have been collected with the specimen (For example, the larvae of some Mycodiplosis species feed primarily on the spores of rust fungi and studies on these larvae have used herbarium specimens dating back to the 1880s);
  • ​Document CO2 changes and minor cycles in climate;
  • Information on expeditions and explorers.

Education and training

  • Material for teaching;
  • Research projects;
  • Run public workshops and awareness programs;
  • Internships and job opportunities;
  • Specimens for museum and educational exhibits.
book frontispiece
Frontispiece to Julius A. Palmer's book About Mushrooms: a guide to the study of esculent and poisonous fungi, published in 1894​.