Kew’s Herbarium contains around seven million preserved vascular plant specimens. These specimens contain a wealth of information about plants that have been collected around the world over the past 170 years.
The Herbarium is a collection of preserved plants that are stored, catalogued, and arranged systematically for study. When specimens are collected in the field, the Herbarium and associated information in the library is used to identify these specimens, to determine how one species differs from another, or whether a specimen represents a species new to science.
Herbarium specimens act as a source of information, to determine: what the plants look like; where they are found; what environmental niche they occupy; which species are threatened by extinction; what morphological and chemical variation occurs; and, when they flower or produce seed. Specimens can be used to provide samples of DNA to study relationships and evolutionary processes. They also act as vouchers to validate scientific observations. The Herbarium is therefore of immense practical use and of fundamental importance to science.
Individual plants (or parts of plants) are preserved, stored and cared for over time so that current and future generations can identify plants, study biodiversity and use the collection in support of conservation, ecology and sustainable development.
The Herbarium holds specimens of vascular plants which include ferns, lycopods, gymnosperms (including conifers and cycads) and flowering plants. Non-vascular plant specimens such as bryophytes (mosses and liverworts) were transferred to the Natural History Museum following an agreement in 1961.
Kew’s Herbarium collection, one of the largest in the world, is representative of global vascular plant diversity, containing around 95% of vascular plant genera and 330,000 type specimens, which act as standards for identifying the correct name for a plant.
Around 25,000 specimens are added to the collection each year, a quarter of which are collected by Kew staff with partners from around the world, the remainder being sent from other herbaria worldwide. Around 12% of the Herbarium collection has been databased; this includes all the type specimens, which have also been imaged.
When William Hooker was appointed Director of Kew in 1841 there was no official herbarium. Before then, Sir Joseph Banks’ herbarium and library in Soho Square had been used for queries on plant names and classification. Hooker then made his own collection, perhaps the largest in private hands, available to staff and visitors at his home close to Kew. The ground floor of Hunter House became available in 1852 and was used to house Hooker’s herbarium, alongside the herbarium and library of Dr William Arnold Bromfield. The first curator, Allan Black, was appointed in 1853. Subsequently, eminent botanists, including George Bentham, donated their own collections to that of the herbarium of William Hooker.
In 1877, the need for greater space, due to botanical exploration of the British Empire, led to the first wing being added. Three further wings were added between 1903 and 1969, with further expansion into the quadrangle in 1989, and a modern wing with climate control was added in 2010.
Although the Herbarium was founded in 1852, many of the subsequently donated collections contained earlier material. An important example of this is the Herbarium of the East India Company, housed separately from the main collection, including Wallich’s collection from British India 1822–1829. The oldest collections in the Kew Herbarium are a few specimens from the Petiver Herbarium, collected by Samuel Brown in India and dated 22–27 April 1696.
A specimen may consist of a whole plant (in the case of small herbs) or parts of a plant (in the case of large trees or bushes). Specimens typically include samples of the leaves, stem, and bark, and ideally should include flowers and/or fruits, since these are of most use later when identifying plants or using the specimens to study relationships between plants. Additional, ancillary collections will often be made at the same time. Exactly what is collected will depend on the plant, but it might include wood samples, dried fruits, flowers preserved in spirit, photographs or DNA samples. Modern collections will typically include latitude and longitude recorded in the field using GPS. Exact localities can be calculated for older specimens using the information recorded on the specimen label and sources such as gazetteers.
Specimens are organised systematically, by family, genus and species, which means that related species are found close to one another thus facilitating their comparison. Herbaria that organise their specimens in this way serve as a working hypothesis for the classification of all plants.
Today, Kew carefully targets new acquisitions. Primarily we work with collections from tropical countries where the flora is less well known and where new plant species are still being discovered. Around 2,000 new species are described every year and about 15% of these new species have types deposited at Kew.
We target new species from particular families, plants from particularly threatened habitats, and plants relevant to our wider research programme. The collection also reflects the specialist skills and interests of staff that work here and that have worked here in the past. Thus, the legume, orchid and palm collections at Kew are particularly rich as many famous botanists specialising in these families have worked at Kew.
Plants are only incorporated into Kew's collection if they have been collected and brought into the UK according to a set of strict procedures established by international treaties such as the Convention on Biological Diversity (CBD) and the Convention on Trade in Endangered Species of Wild Fauna and Flora (CITES).
The specimens and the information derived from them are used to answer key questions underpinning our understanding of plant diversity, conservation and sustainable use. These questions are outlined in Kew’s Science Strategy 2015–2020:
Over 400 scientists visit the Herbarium each year from other institutions to study our collections for their research, ranging from plant taxonomy and evolutionary studies to conservation planning, agricultural research, environmental and climate science. These visitors also add value to the collections by updating their curation. Kew also sends out around 10,000 specimens each year as loan or exchange material to scientists worldwide. Other academics such as historians use the collections as records of discovery, exploration or collaborations over the past 250 years.
The Herbarium is open to academic visitors upon request and to the public via special events such as open days.
Royal Botanic Gardens, Kew
Surrey TW9 3AE
9am to 5.30pm Monday to Thursday
9am to 5pm Friday
Closed weekends and public holidays