A herbarium is a collection of dried, pressed plants fixed to sheets of paper. In this form, specimens can be stored virtually for ever if they are protected from water and insects. The individual sheets may be labelled with a whole variety of information, such as the scientific name of the plant, its location, the name of its collector, date of its collection, habitat details, features such as flower colour or scent, economic uses, and so on. So each herbarium sheet is an important reference point for botanical studies, but is also a historic document at the same time.
The Herbarium at Cambridge University has over 1 million sheets. Its oldest dated specimens found so far date from 1703, and new ones are still being added every year. There are plants from across the whole world, with a superb collection from Britain and Europe numbering about half a million sheets. The Herbarium is thus a biological time-line now spanning 300 years of history. Its precious possessions include Prof. John Henslow's own unique research herbarium as well as the plants which Charles Darwin collected for his mentor, Henslow, on the voyage of HMS Beagle.
A particularly important feature of the Herbarium lies in its type specimens, which may number as many as 50,000. These sheets carry the very plants which were used as the basis of the descriptions of new species as they were discovered, and so are the essential reference points for all studies of plant diversity. The Herbarium has wonderful collections made by John Lindley, who was the secretary of the Royal Horticultural Society in the early 19th century. He received seeds from collectors all over the world, grew them in the Society’s glasshouses and garden in London, and described many species previously unknown to science.
Curation and Conservation
Herbarium specimens need constant care and attention. Ideally, they should be kept up to date with modern taxonomy and they require conservation. Currently, the Darwin collection is being restored by Emma Ruffle, funded by a donation from Lawrence Banks, to preserve this priceless collection for future generations to study.