• Last updated:
  • 07 Jun 2018

Did you know Melastoma can be a weed? 

There seems to be an increase in cases of the introduced species Melastoma candidum occurring around the Sunshine Coast. It’s very easily confused with the native variety Melastoma malabathricum and there is little information or awareness surrounding the current problem.

The introduced species is an invasive shrub that can spread rapidly and seems to readily naturalise better than the native variety. It is capable of forming dense monotypic thickets in a selection of different habitats such as shrubland, open land, grassland, native forest and wetlands. It originates from Southeast Asia however there are some key features that can easily separate the introduced species from its native look-a-like.

The best way to tell if it's the native variety is by looking closely at a number of leaves on the plant and counting the number of longitudinal veins and intramarginal veins. Melastoma malabathricum (the native) will have three distinct longitudinal veins while the outside of the leaf has two more indistinct intramarginal veins. The exotic Melastoma candidum has two extra longitudinal veins and two less distinct intramarginal veins on the outside of the leaf. The adjoining pictures outline just how easy it is to tell the difference between both species by looking closely at the veins on the leaves.

There have been various studies carried out where it has been a problem for some time in Hawaii with biological control and chemical control. It is recommended to pull them out by hand where possible when they are a small specimen as Glyphosate 360 has shown signs of resistance.

 Characteristics

Melastoma malabathricum subsp malabathricum (was Melastoma affine)

Melastoma candidum (also known as Melastoma septemnervium)
 Common name Blue Tongue or Native Lassiandra Asian Melastoma
 Flower Pink flower (also a white form), 5 petals, about 20-30mm long More purple and larger flower, 5 petals, about 25-32mm long
 Leaves Generally have 3 longitudinal veins and 2 indistinct intramarginal veins. Leaf is thinner than the exotic and leaf hairs seem slightly shorter Generally has 5 longitudinal veins and 2 indistinct intramarginal veins. Leak is thicker and stiffer than the native and leaf hairs seem slightly longer
 Fruit Purple blue in colour Bright raspberry red in colour
 Size Usually grows to 1-2 metres Grows to a good 2 metres and is more dense and robust than the native