What’s in a name? New version of The Plant List released

Alan Paton, Assistant Keeper of Kew's Herbarium, describes some of the problems associated with plant names and the importance of the new release of The Plant List.

Interior shot of the Palm House canopy

How do I communicate about plants? How do I tell you that one particular plant makes a very good herbal tea, or that another is highly toxic?

The obvious answer is that I would use its name: a fundamental starting point for both social and scientific interactions involving plants. However, people from different countries or backgrounds use different common names for the same plant and, in addition, a single common name can refer to more than one plant species.

The common name laurel can refer to very different plants. From left to right: Laurus nobilis L., laurel or bay, used in cooking; Prunus laurocerasus L., laurel or cherry laurel (poisonous); and Daphne laureola L., daphne laurel or spurge laurel (poisonous). (Photos: Elizabeth Dauncey)

The confusion that surrounds common names means that the use of scientific Latin names is the preferred convention. Each published Latin name is attached to a ‘type specimen’, a herbarium specimen, that epitomises the characteristics of that species. No such definitive reference exists for common names.

    However, even using Latin names poses challenges. There are around 380,000 species of vascular plants, but over a million scientific Latin names for these at species level. These multiple names (synonyms) arise because plant species can be described and named by different people at different times and different places. Scientific Latin names also change when botanists re-evaluate a plant’s evolutionary relationships and place it in a different genus. The problem of synonymy is particularly pronounced for plants widely used by humans, which tend to have more Latin names ascribed to them.

    A recent survey of some common medicinal plants by Kew’s Medicinal Plant Name Services project (MPNS) suggests that, on average, medicinal plants considered by that project have eight scientific Latin synonyms. This causes problems if we wish to gather all the information about a particular medicinal plant.

    For example, the genus Plectranthus, is widely used as a medicinal herb in India and Africa. Thirty percent of over 700 citations on the uses and chemistry of these plants use synonyms rather than the currently accepted name for Plectranthus species. Therefore, a search for information using only the currently accepted name, rather than all the available names for a particular species, may miss a third of the relevant information in the literature. The situation is much worse for the five most used medicinal species of Plectranthus where only 20% of the literature used the currently accepted name.

      An accessible list of plant names and their synonyms

      A list providing the accepted scientific Latin name for a plant species and linking it to all of its Latin synonyms is an invaluable tool for pulling information together from a variety of disparate sources. One of the major impacts of such a widely accessible list is that it provides a source of species information and nomenclatural data for other information systems. The list also may be used as a tool in its own right for checking the status of a plant name.

      Kew, in association with Missouri Botanical Garden, and several other collaborators, has just released a new version of The Plant List, a working list of known plant species. Version 1.0 was produced in December 2010 as a response to the Global Strategy for Plant Conservation (GSPC), adopted in 2002 by the 193 governments who are parties to the Convention on Biological Diversity.

      The GSPC was designed as a framework for action to halt the loss of plant diversity. Target 1 of the Strategy called for the completion by 2010 of a widely accessible working list of all known plant species, as a step towards a complete World Flora. Released in December 2010, Version 1.0 of The Plant List aimed to be comprehensive for species of vascular plants (flowering plants, conifers, ferns and their allies) and of bryophytes (mosses and liverworts), responding to this call and to a clear global need for such data.

      The revised edition (TPL1.1) resolves some data quality issues and contains a Rosaceae data set supplied from Richard Pankhurst from Edinburgh Botanical Garden. The Plant List Version 1.1 will be an important resource for facilitating the revised Target 1 of the GSPC for 2020: the production of an Online World Flora. This version includes 1,064,035 scientific plant names of species rank. Of these 350,699 (33%) are accepted species names, 44% are synonyms and 23% are unresolved (these latter requiring further work to determine their status).

        Assembling The Plant List

        Assembling The Plant List has been a collaborative venture coordinated by botanists and IT specialists at the Royal Botanic Gardens, Kew and Missouri Botanical Garden and has relied on the generosity of many collaborators who manage significant taxonomic data resources. The purpose was to merge into a single consistent database the best of the nomenclatural information available in these diverse data resources through a defined and automated process.

        Development of The Plant List involved merging many taxonomic data sources. This sounds straightforward but is challenging intellectually and from an IT perspective. We took the accepted names and synonymy relationships from global checklist datasets, and augmented these by adding additional names and synonymy relationships from various regional and national floristic datasets using a sequence of logical rules. Species names not accounted for in any of the previously incorporated data sets are added from nomenclatural resources, ensuring the list is comprehensive for all plant names. Finally, a further set of rules is applied to the final data set to resolve inconsistencies, conflicting or overlapping status and to correct logical data errors.

          The Plant List is static. It is neither updated regularly from the original data sources, nor edited directly. Feedback and corrections pertaining to its records are passed onto the source database for consideration. If accepted by the source database, they may be incorporated in a future version. The Plant List represents work in progress. Data comes from a variety of sources which are both monographic (global) and regional in scope and these data sources vary in the extent to which comprehensive synonymy is included, their stage of development and the degree to which they have been exposed to peer review.

          The Plant List indicates the confidence which can be given to the status of a particular name record using a star rating. The ‘unresolved’ status indicates that the data sources included provided no evidence or view as to whether the name should be treated as ‘accepted’ or not. There are other reliable authoritative sources of taxonomic opinion for some groups or some regions which we simply did not have the time or resources to include in this version of The Plant List. Our ambition is for future versions to be more inclusive and comprehensive.

          Despite the above limitations there is huge demand for this working list: there have been 2.25 million visits and 1.2 million unique visitors over the last year. Of course, a large number of people still want to use common names. Linking common names in different languages to their corresponding Latin names remains a significant challenge, but a consistent comprehensive working list of known species using Latin names is a necessary first step. The release of the Medicinal Plant Names Service portal in spring this year will be Kew’s first attempt to include common and other names such as pharmaceutical names in a search portal.


            • Paton, A. J. (2013). From Working List to Online Flora of All Known Plants—Looking Forward with Hind-sight. Annals of Missouri Botanical Garden 99: 206-213.
            • Paton, A. J., Brummitt, N., Govaerts, R., Harman, K., Hinchcliffe, S., Allkin, B., & Lughadha, E. N. (2008). Towards target 1 of the global strategy for plant conservation: a working list of all known plant speciesprogress and prospects. Taxon 57(2): 602-611.
            • Lukhoba, C. W., Simmonds, M. S., & Paton, A. J. (2006). Plectranthus: A review of ethnobotanical uses. Journal of Ethnopharmacology 103(1): 1-24.

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