With thousands of species, many known from only a handful of places, the Melastomataceae contains a large number of plants whose futures are uncertain. Some are common weeds. Many others are narrow endemics, found on a single mountain, in a single valley or in a few forest fragments.
Main threats
Habitat loss. The biggest pressure on most species is the clearing of forest for agriculture, pasture, plantations, mining and settlement. The Atlantic Forest of Brazil, home to many melastomes such as Bertolonia, is commonly cited as having lost most of its original cover. Andean cloud forests and Southeast Asian lowland forests face similar pressure.
Fragmentation. Even where forest remains, it may be broken into small patches. Small populations are more vulnerable to chance events and to loss of pollinators or seed dispersers.
Climate change. Species restricted to narrow elevation bands, such as the shrubs described in Brachyotum, may lose habitat as zones shift upslope. Changes in cloud cover and rainfall patterns could also affect species that rely on constant humidity.
Invasive species. On islands especially, invasive plants, including some melastomes, can displace natives (why some melastomes are invasive).
Overcollection. Rare ornamental species can be collected from the wild for the plant trade. Foliage herbs of the kind covered in Sonerila are particularly at risk if wild-collected.
The data problem
You cannot protect a species you do not know about. Many melastomes are known from very few specimens, and some have not been seen since they were first collected. Conservation status assessments exist for a growing number of species, notably through the IUCN Red List, but a large proportion of the family has not been assessed or is classed as data deficient.
This is where herbaria matter. Specimens record when and where a species was found, which helps researchers map ranges and detect declines. See herbaria: where melastome species are preserved. New species are also still being found and named (how new species get described), and some of them are discovered already threatened.
What helps
- Protecting habitat, especially in biodiversity hotspots with many endemic species.
- Surveys and monitoring, to find out whether rare species are still present.
- Ex situ conservation, growing rare species in botanic gardens and seed banks as a safeguard, though this can be difficult for species with specialised needs.
- Controlling invasive species on vulnerable islands.
- Supporting responsible horticulture, which means buying nursery-propagated plants.
What individuals can do
- Buy plants from reputable nurseries that propagate their own stock, and avoid wild-collected plants.
- Never plant species known to be invasive in your region.
- Support botanic gardens, herbaria and conservation organisations.
- Record observations of plants through citizen science platforms where appropriate.
Takeaways
- Habitat loss is the main threat to melastomes.
- Many species are poorly known, so data collection is crucial.
- Herbaria, botanic gardens and responsible gardening all help.