Why Some Melastomes Are Considered Invasive Weeds

A recurring theme on this site is how easy many melastomes are to grow — tolerant of a range of soils, fast to establish, and reliably showy. Those exact same traits are also the reason a small number of species have become serious invasive problems outside their native range.

The traits behind the problem

Fast growth, prolific seed or berry production, bird- or bat-dispersed fruit, and tolerance of disturbed ground are all genuinely useful traits for a plant trying to survive in its native tropical forest. Move that same plant somewhere with no natural predators, competitors, or diseases to keep it in check, and those traits can let it spread largely unchecked.

Miconia calvescens, covered in more detail in our Miconia genus profile, is the most cited example — introduced to Pacific islands as an ornamental, it has since displaced native forest across large areas of Tahiti and parts of Hawaii. Melastoma species, including Melastoma malabathricum, are flagged as problematic weeds in some agricultural regions for similar reasons, even though the same species is a completely unremarkable, non-problematic native plant elsewhere in its range.

Native versus invasive isn't about the plant alone

This is a useful, easy-to-miss distinction: whether a species counts as "invasive" depends entirely on location, not on some inherent property of the plant itself. A species can be an ecologically unremarkable, even ecologically important, native plant in one region and a genuinely destructive invasive in another, with nothing about the plant itself having changed.

What this means for growers

If you're growing melastomes outside their native range — which describes most home gardeners reading this — it's worth checking your local invasive species list before planting anything in open ground, rather than relying on how the plant behaves elsewhere. Container growing largely avoids this concern, since it prevents uncontrolled spread by seed.