How herbarium specimens are prepared
Learn how plant specimens are collected and preserved at Cambridge University Herbarium
By Cambridge University Herbarium
Video presented by Anne Dubéarnès and produced by Graham Copekoga of the Cambridge Philosophical Society.
Collecting from the wild
Plants have been gathered, dried and preserved for hundreds of years. These specimens allow researchers to understand plant structure, distribution, and the historical context in which the specimens were collected.
Herbarium specimens allow researchers to study threatened species, like these English bluebells, in order to protect wild populations.
Collection notes
When a plant is collected with the intention of creating a herbarium specimen, the collector keeps notes of when and where each plant was gathered, usually in a field notebook, and gives each plant a collection number.
Habitat and plant characteristics
Collectors also make notes about the habitat and characteristics of the plant. This detailed information is what turns a pressed plant into an object that is useful for scientific research.
Pressing and drying
Plants must be dried quickly to prevent rotting and to maintain the structure and colour of the plant, as well as its potential for DNA extraction in the future.
Some specimens which were dried quickly and carefully preserved have retained their colour over a hundred years later.
Freezing specimens
When the plants are dry, they are carefully frozen for 72 hours at -40 Celsius to ensure no pests are introduced into the collection.
Creating herbarium sheets
The plants are then mounted on acid-free archival paper using linen tape lined with water-activated adhesive. Specimens are arranged in a way that shows all of the plant's important characteristics for identification, including flowers, fruits and both sides of the leaves.
Sometimes large specimens may be divided over multiple sheets to show all parts of the plant, as with this leek.
Labels
A label listing the plant name, collection number, location, date, habitat, and collector name is glued to the sheet to ensure that the plant and its relevant information remain linked.
Storing herbarium sheets
The specimen is then laid away in the collection, which is arranged by world region and plant family, genus and species.
Digitising herbarium collections
When a researcher inquires about a particular plant, the curatorial team locates the specimen and makes it available to the researcher in person or by sending photos of the sheet. Our digitisation program helps us preserve specimens and simultaneously make them more accessible.
See how specimens are prepared, stored and used with taxonomist Anne Dubéarnès.
Sally Loesch and Anne Dubéarnès for Cambridge University Herbarium.
Video presented by Anne Dubéarnès and produced by Graham Copekoga of the Cambridge Philosophical Society.
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