Ask how many species are in the Melastomataceae, and you will get different answers depending on where you look. This is not sloppy counting. It reflects how plant taxonomy works.
Rough figures. Genera: somewhere between about 170 and 200. Species: roughly 4,500 to 5,800 or more. The family is one of the larger flowering plant families, and by far the largest among the tropical shrubs and small trees of the Neotropics.
Why the numbers differ
Different definitions. Whether a particular group counts as part of Melastomataceae affects the total. The Memecylon group, for example, is sometimes included and sometimes treated as a separate family (Memecylon).
Splitting and lumping. Taxonomists differ in how narrowly they define genera and species. Splitting a genus into several increases the genus count, and merging genera reduces it. The reclassification described in Tibouchina and Pleroma is a recent example.
New discoveries. Species are still being described, so the total keeps rising. See how new species get described.
Synonyms. Many names turn out to refer to the same species. Removing duplicates lowers counts. See synonyms and accepted names.
Different publication dates. A figure from a book published in 2005 will differ from a database updated last month.
The largest genera
Sizes below are approximate and change as classifications are updated.
| Genus | Approx. species | Region |
|---|---|---|
| Miconia | 1,000 or more | Neotropics |
| Medinilla | around 400 | Old World tropics |
| Sonerila | well over 100 | tropical Asia |
| Blakea | around 100 | Neotropics |
For profiles, see Miconia, Medinilla, Sonerila and Blakea.
A family of many small genera
Beyond the giants, the family includes many small genera, some containing only one or two species. Many are restricted to a single region. This long tail of small groups is a major reason the genus count is so sensitive to taxonomic opinion.
Where the diversity is
Most species occur in the Americas, as described in where melastomes grow. The Andes, Amazon, Guiana Shield, Central America and Brazil's Atlantic Forest are all rich in species.
Why the count matters
Species counts guide decisions about where to focus conservation and research. A region with many narrow endemics is a priority for protection (conservation of melastomes). Knowing roughly how many species exist also helps researchers estimate how many remain undescribed.
How to quote the numbers
If you are writing about the family, a safe approach is to give a range and the source, for example: "about 170 to 200 genera and more than 4,500 species, depending on the classification followed". If you need exact current figures, check an up-to-date database such as Plants of the World Online and cite the date.
Takeaways
- No single correct count exists, and figures vary with definitions and dates.
- Miconia is by far the largest genus.
- The long tail of small genera makes the genus count especially sensitive.
- When quoting numbers, give a range and a source.