Wild Bananas of Ulu Temburong

There are an estimated 75 species of wild bananas in the world with a native distribution from the Himalayas to New Guinea. Borneo with 16 native wild species (15 endemics) is the world center of distribution.  Within Borneo, the hills from Central Sarawak north to Kinabalu host the majority of Borneo’s banana species. Ulu Temburong is therefore right at the heart of world banana diversity. Four common wild bananas that grow next to the Ulu Ulu Resort are illustrated in this article. Several additional wild species grow along  the two rivers, Sungai Temburong and Sungai Belalong upstream from the Ulu Ulu resort.

PINK BANANA Musa campestris. With bananas, male and female flowers are contained within the same bud  in multiple layers which open layer by layer. The female flowers  are in the outer layers of the bud and the male flowers within the inner layers. The photo shows an open outer layer of the female flowers. After pollination the base of each female flower forms a banana fruit.

PINK BANANA Musa campestris growing behind the Ulu Ulu resort.  The female flowers have all opened and formed bananas and  the pink bud  now contains only male flowers – which look like a bunch of cigarettes at the base of the bud. The Pink Banana is the most common wild banana in  Brunei and lowland Sarawak. It is less common in Sabah.  Wild banana fruit in Borneo are usually not eaten because they are full of seeds, however locals often cut off the male bud  (jantung or heart in Malay)  which is sliced and cooked as a vegetable.

BORNEAN BANANA Musa borneensis growing in the garden of the Belalong Field Centre about 500m upstream from the Ulu Ulu Resort. Note that all the female flowers have already been pollinated creating the bunch of green bananas at the top of the stalk. The yellow “jantung”  or bud therefore  contains only male flowers.  The reason that each banana flower opens female flowers first and male flowers later over a period of weeks  is to avoid self-pollination, by bats or birds that come to feed on the flower nectar.

BORNEAN BANANA Musa borneensis is a common wild banana found throughout the hill forests of Borneo. Note that although the yellow jantung hangs down, the flowers at top left point upwards. The open end of the flowers are protected from rain by a bract  “roof”. The brown scratches on the jantung are from the claws of  Bornean Spiderhunters, Arachnothera everetti that arrive to feed on the nectar  and so carry pollen from one banana clump to another. The flowers face up and outwards to make it difficult for nectar bats to access the flowers as bats will have probably just visited a different species of  “bat” banana and will be carrying the “wrong” pollen .

TINY BANANA  Musa acuminata var microcarpa is a very close relative of  the many cultivated bananas which are grown in Borneo. Musa acuminata var microcarpa also grows wild in Borneo. This wild variety has very small fruit hence the latin name “microcarpa” meaning tiny fruit. Notice the the bracts covering the male bud or jantung have longitudinal grooves as with typical  cultivated bananas in Borneo. Wild Musa acuminata bananas are pollinated by nectar bats which cling onto the jantung as they sip nectar from the flowers (which look like cigarettes)  which open downwards.

MULU BANANA Musa muluensis growing next to the Ulu Ulu Resort at Temburong in Brunei. The flower bud  and the male flowers hang down like Musa acuminata (above) indicating that M. muluensis is also pollinated by nectar bats. The male flowers on this jantung  bud have already fallen off after providing pollen to visiting bats. In the evening another bract will open exposing a bunch of male flowers to bats all night. Note that of the four wild banana species growing at Ulu Ulu there are three different pollination strategies.  (1) Musa campestris targets Lesser Spiderhunter birds-bracts open during the day  (2) Musa borneensis targets Bornean spiderhunters with stronger bills- bracts open during the day (3) Musa acuminata and Musa muluensis both target nectar bats with bracts that open  and expose a fresh layer of flowers  each evening at dusk.