Classifying plants and fungi at Kew

Kew's taxonomists are the botanists and mycologists who specialise in identifying, naming and classifying plants and fungi.

Underpinning their work are Kew’s collections. Kew's Herbarium contains seven million preserved plant specimens, representing about 98% of the world’s genera and 75% of the world's plant species. Our fungal collection holds over 1.25 million specimens, making it one of the most comprehensive collections of its kind in the world. Meanwhile the Gardens themselves contain over 19,300 living plants and are home to over 2,700 species of fungi.

Tahina spectabilis

The need for knowledge

We still have much to learn about the world’s plants and fungi. Scientists estimate that 15-20% of plant species have not yet been described. And at present, about 2,000 new species of plants are discovered every year. A recent new discovery made by Kew's taxonomists is the suicide palm (Tahina spectabilis) of Madagascar.  This plant grows to 18 metres tall before flowering itself to death. Our knowledge of fungi is even less extensive; as many as 90% of the estimated 1.5 million species that exist have yet to be named.

Putting plants in their place

Botanists group plants that are related to each other into families, which are further divided into genera and species. Specimens in Kew’s Herbarium collections are arranged in such a systematic way. This means that if someone has a specimen to identify that is similar to one in the collection, they are likely to find the matching plant close by. If the plants were arranged alphabetically it would be much harder to make those links.

Traditionally, Kew has used the Bentham & Hooker system of plant classification, which mainly groups plants by visible characteristics, i.e. their morphology. From 2010 Kew started to re-organise its Herbarium according to the new APGIII classification, which relies heavily on plant relationships determined by DNA analysis.

Using state-of-the-art tools

Morphological similarities between groups of plants do not always reflect true evolutionary relationships. Information from DNA sequences are now revealing relationships that were previously unknown.

In the plant kingdom for example, peonies once thought to be related to buttercups because of their visual similarities, are in fact closer to saxifrages. While papayas have more affinity with cabbages than passion flowers.

In the fungi kingdom, puff balls previously placed in in the ill-defined group 'Gasteromycetes,' are now known to be close relatives of the agarics, which include the familiar mushrooms and toadstools.

In studying further such unexpected relationships of plants, Kew scientists examine other characteristics and traits, such as microscopic structure, pollen and chemistry. In 2010 Kew decided to adopt the new APGIII system of plant classification based on DNA sequence data. Some of our fungal collections are already arranged according to relationships deduced from DNA.