Plant names change. A species can be moved to a different genus, merged with another species or split into two. The result is that a single plant may have several names in circulation. Understanding how to sort them out is a core plant-research skill.
Key terms
- Accepted name: the name currently regarded as correct by a given authority.
- Synonym: another name that refers to the same plant, which is no longer preferred. Synonyms may be older names or names published in error.
- Basionym: the original name on which a new combination is based.
- Homotypic synonym: an alternative name based on the same type specimen, for example when a species is moved to a new genus.
- Heterotypic synonym: a name based on a different type specimen but now judged to describe the same species.
Why names change
- Reclassification. New evidence shows a genus is not a natural group, as with Tibouchina and Pleroma.
- Priority. If two names exist for the same plant, the earliest validly published one generally wins.
- Lumping and splitting. Two forms once considered separate species may be merged, or one species divided.
- Correction of errors. Sometimes a plant was named incorrectly or a name was illegitimate.
Where to check
Several free resources are widely used. No single one is perfect, so cross-checking is a good habit.
- Plants of the World Online (POWO): from the Royal Botanic Gardens, Kew. Gives accepted names, synonyms and distribution.
- International Plant Names Index (IPNI): records published plant names with original citations. It tells you that a name exists, not whether it is accepted.
- World Flora Online: a collaborative global checklist.
- Tropicos: from the Missouri Botanical Garden, with strong coverage of Neotropical plants including many melastomes.
- GBIF: the Global Biodiversity Information Facility, which compiles specimen and observation records and uses a backbone taxonomy.
A simple checking routine
- Search the name you have in POWO or World Flora Online.
- Note whether it is listed as accepted or as a synonym. If it is a synonym, record the accepted name.
- Check IPNI for the original publication if you need the author citation.
- For Neotropical plants, check Tropicos or a regional flora for context.
- If sources disagree, say so, and state which one you are following.
Writing it up
In scientific writing, the usual convention is to give the accepted name first, followed by the synonym in parentheses: Pleroma urvilleanum (syn. Tibouchina urvilleana). For gardeners and general readers, giving both names helps everyone find information.
Author citations
The names that follow a scientific name, such as Juss. or DC., identify who named it. These help disambiguate names. See reading a botanical name for a beginner's guide.
Takeaways
- A plant can have one accepted name and several synonyms.
- Use databases such as POWO, IPNI, World Flora Online and Tropicos.
- Cross-check, and cite which source you are following.
- Provide both names when writing for general readers.