Melastoma malabathricum - Singapore rhododendron

One of the plants which is native to Singapore is the Melastoma malabathricum or Singapore rhododendron. It is found throughout Singapore, usually growing wildly along roadsides and in particular, wastelands. I chanced upon these growing in the garden at my new house. There were possibly various species but the more common ones had pink and white blooms. I like how it grows into this dense and compact shrub which makes it ideal as a potted plant. In fact, this plant has medicinal qualities, which explains why AMK nursery is selling them at the herb section.

An article by Wilson Wong of GreenCultures 20 August 2008 is reproduced below:-

Melastoma malabathricum, commonly known as the Singapore Rhododendron, is a flowering shrub that can be found growing locally in wastelands. As a result, it is not surprising to know that most Singaporeans regarded it as a weed and this plant is seldom considered as a candidate for planting a home garden. The Singapore Rhododendron belongs to the Melastoma family, Melastomaceae. It is alternatively known by its Malay name, Sendudok.

Although the name “Singapore Rhododendron” may make M. malabathricum sound as if it can only be found here, the plant, in fact, has a wide
distribution around this part of the world. It has been reported to be found growing wild in the Indian Ocean Islands, throughout South and South-East Asia, China, Taiwan, Australia and the South Pacific Ocean.

For those who have seen M. malabathricum before, they would have noticed that it is a showy plant that seems to be perpetually in flower, even under
challenging environmental conditions encountered in wasteland, where the sun is glaring and nutrients and water are lacking. It deserves more attention and can be a potential fuss-free flowering ornamental plant to grow in the garden. A shrub that usually grows to about 1 m, the reddish stems and leaves of M. malabathricum are rough to the touch as they are covered with fine bristles. Each leaf is long and narrow and pointed at both ends. It has 3 distinct ribs and the fine bristles can be found only along on the ribs located on the leaf’s underside.

The attractive flowers produced by M. malabathricum, measuring up to 7 cm in diameter, are produced in a cluster at the tip of each shoot. Each flower
has five petals and the most common flower colour is deep mauve. Occurring less commonly is the white flowered cultivar that is known as M. malabathricum ‘Alba’.

The flowers are interesting as they have two types of stamens – the anthers of five outer stamens, arranged in an outer ring are larger, curved and
violet in colour while the remaining five located in an inner ring are straight and yellow in colour.

Fruits of M. malabathricum are technically classified as berries and when they are ripe, they break open irregularly to reveal the soft, dark purple, sweet
but rather astringent-tasting pulp and numerous orange seeds. The seeds are tasteless and can be eaten and they stain the tongue black. The name
“melastoma” is Greek for "black mouth", a name appreciated by generations of children who have eaten the berries.

Melastoma malabathricum has medicinal properties particularly the white flowered form and is a pretty candidate to grow in a tropical medicinal garden. It
is a well-known herb where its leaves, shoots and roots are prepared in various ways and used to treat stomachache and diarrhoea. The roots and leaves of the M. malabathricum are applied to lesions and wounds to help with the healing process and also in the treatment of haemorrhoids.

This beautiful, medicinal shrub may sometimes be confused with the Rose Myrtle (Rhodomyrtus tormentosa), which is another medicinal plant. Both shrubs
have leaves that have three prominent ribs and are rough to feel. They can be easily distinguished easily as the leaves of the Rose Myrtle end with a blunt tip whereas those of M. malabathricum are pointed.

To add to the confusion, the fruits of both shrubs have a ring of persistent calyx lobes. The fruits of the Rose Myrtle are larger and when they are ripe, the
fruits turn greyish purple in colour. On the other hand, the fruits of M. malabathricum are usually smaller in size and when they are ripe, the fruit’s rind
is reddish brown or green in colour.

The flowers of M. malabathricum are also larger than those of the Rose Myrtle and can be told apart from the latter’s via the appearance of the anthers.
Melastoma malabathricum has ten distinct anthers whereas those of the Rose Myrtle are far more numerous and fine. Only the flowers of the Rose Myrtle
change colour with age – they are pink when freshly open and fade to almost white.

A flowering shrub that should be grown in any eco-garden, M. malabathricum is a plant that attracts many birds including the yellow vented bul
bul, flowerpeckers, doves and pigeons which consume the ripe fruits and help to disperse its seeds. Squirrels and monkeys are also fond of the fruits. The plant is the host for caterpillars of butterflies such as the Common Sailor (Neptis hylas) and the Grey Count (Tanaecia lepidea).

Although the plant has earned itself a “weed” status, in addition to its use in sustaining wild life, it has an important contribution to the wasteland it colonises because it helps to prevent soil erosion. Research has shown that M. malabathricum is a plant that is very efficient in absorbing aluminium ions from the ground where it is grown. Hence it has the potential to be used to remove aluminium from soils that have been contaminated with the metal.

For garden use, M. malabathricum is a full sun plant, judging from its growing habit, i.e. open wasteland. In order for the plant to grow healthily and
flower profusely, the shrub needs to be planted in a location where it can receive direct sunshine.

This flowering shrub is not fussy about soil type and M. malabathricum can also be grown in areas with clayey soil but it definitely does better in soil that
is fertile and friable. It should be noted that its roots should be consistently moist and plants should not be allowed to dry out between watering. It is a suitable candidate as a marginal plant for bogs and water gardens.

Plants should be pruned back to shape them and because of its self-seeding habit, shrubs in bloom should have their spent flowers removed
promptly, that is, dead-heading, is required to limit fruit and subsequent seed production.

Although it is a plant that is adapted to nutrient-poor conditions, M. malabathricum would definitely benefit from a regular dose of a general fertilizer
to promote healthy growth and produce a profusion of flowers. Plants can be easily propagated from seeds if they are taken from fresh, mature fruits. Alternatively, a faster way to get new plants is to grow them from stem-cuttings.

Melastoma malabathricum is seldom bothered by pests and diseases. Being a host plant for certain caterpillars, do expect some damage to the plant’s
foliage when it is the season where butterflies start to lay their eggs. The plant is the host for caterpillars of butterflies such as the Common Sailor (Neptis hylas) and the Grey Count (Tanaecia lepidea).

Being among the first to colonise wasteland, the plant helps prevent soil erosion and to allow regeneration of vegetation in such places.