In recent years, the introduction of the exotic Asian Melastome (Melastoma
candidum) has been a source of concern as it is similar in appearance and often confused with the native Blue Tongue ( Melastoma malabathricum subsp. malabathricum ). The purple fruit of native Blue Tongue is sweet and edible, and once eaten, it turns tongues a blue-purple colour, hence the common name.
Asian Melastome, native to tropical Asia, is cultivated as an ornamental shrub. Readily spread by birds, it has become an invasive garden escapee in tropical and sub-tropical areas including in Australia, Hawaii and Southeast Asia. Although not a declared weed species in Australia, Asian Melastome is known to rapidly spread, naturalise and form dense thickets in a variety of habitats including eucalypt forests, open land and wetlands.
When purchasing Blue Tongue, check to see if the plant is in keeping with the diagnostic features outlined below. In particular, examine the veins on the leaves. It is important to examine several mature leaves to confirm the number of veins present as there can be some variation. Only the introduced species will have five distinct longitudinal veins. If you are not sure, contact your Land for Wildlife Officer or the Queensland Herbarium to have a plant sample positively identified.
The recommended treatment for adult plants of Asian Melastome is the cut stump method with glyphosate 1:5 in water or Vigilant (Picloram) gel neat. Basal barking can also be effective with Fluroxypyr 333gL (e.g. Starane Advanced) 30ml per litre of diesel or other recommended mixing agent.
Article by Amanda Maggs Land for Wildlife Officer Brisbane City Council
Photos by Deborah Metters
Blue Tongue or Native Lassiandra
Melastoma malabathricum subsp. malabathricum
(was Melastoma affine )
Leaves: Generally 3 distinct longitudinal veins and 2 less distinct intramarginal veins. Leaves hairy but thinner than Asian Melastome. Leaf stalks purple or white with short hairs.
Flowers: Pinkish purple flower (also a white form). Five petals about 20-30mm long. Flowers all year round.
Fruit: Red and green outside, purple on inside, hairy to 10mm.
Habit: Shrub 1-2 metres high, growing in moist areas such as gullies and freshwater wetlands.
(also known as Melastoma septemnervium)
Leaves: Generally 5 distinct longitudinal veins and 2 less distinct intramarginal veins. Leaves hairy but thicker and stiffer than Blue Tongue. Leaf stalks purple or white with long hairs.
Flowers: More purple and a larger flower than the native Blue Tongue. Five petals about 25-32mm long.
Fruit: Bright raspberry red in colour.
Habit: Grows to 2 metres high and is more dense and robust than the native Blue Tongue.