Octomeles sumatrana Miq.
Family
Datiscaceae
Synonyms
O. moluccana Teijsm. & Binnend. ex Hassk.
Vernacular Names
| Indonesia | Benuang, winuang, binuang bini (General). |
| Papua New Guinea | Erima, irima, ilimo (General). |
| Philippines | bilus (Tagalog), barong (northern Luzon), barousan (southern Luzon). |
Geographical Distributions
Octomeles sumatrana is a monotypic genus that occurs in Sumatra, Borneo, Sulawesi, the Moluccas, the Philippines, New Guinea and the Solomon Islands.
Description
O. sumatrana is a large to very large dioecious evergreen trees, which can reach up to measure about 60(-75) m tall. The bole is cylindrical, straight, branchless for up to measure about 30(-40) m, with a size up to measure about 250(-400) cm in diametre while the prominent buttresses are up to measuring 6 m high. The bark surface is fissured or irregularly cracked and often pustular, grey to grey-brown in colour. The inner bark is fibrous, yellowish but rapidly turns brown on exposure and without exudates. The crown is open, pagoda-like with whorled branches when young and semi-globular when mature. The twigs are sharply 3-angled.
The leaves are arranged spirally, simple and entire, thin, roundish cordate, with a size of measure about 12-30 cm x 6-23 cm, acuminate, with 5-7(-9) palmate veins, minutely scaly and below with large domatial glands in the axils of the main veins. The petiole is measuring 6-30 cm long. The stipules are absent.
The flowers are unisexual, actinomorphic, sessile, with 5-8-merous, green and in solitary axillary spikes. The male inflorescence is a measure about 20-60 cm long. The measuring of 4-5 mm x 5 mm flowers is bell-shaped. The petals are with an incurved appendage and with kidney-shaped anthers. The female inflorescence is a measure about 8-12 cm long, with a size of measure about 5 mm long flowers. The sepal is bell-shaped while petals are absent. The ovary is inferior, 1-celled, with 3-8 parietal placentae and many ovules. The styles are 5-8, which are inserted on the throat of the sepal tube while the stigma is capitate. The infructescence is measure about 15-40 cm long and it is on a measuring 10-20 cm long peduncle.
The size of measure about 12 mm long fruit is a barrel-shaped capsule and splits from the top downwards. The spindle-shaped seeds are many and they are measure about 1 mm x 0.2 mm.
Ecology / Cultivation
O. sumatrana grows in lowland evergreen rain forest, up to 1000 m altitude. It is especially common in natural secondary and seral riverine alluvial forest where it is sometimes found in even-aged pure stands. O. sumatrana is a pioneer of bare alluvial soil, binding the soil with a network of roots and thus improving the site. As such it precedes the successional stage of mixed lowland rain forest in which it may occur scattered. O. sumatrana grows naturally in various other open locations such as on volcanic deposits and abandoned logging roads. In Sabah, O. sumatrana is frequently associated with kadam (Anthocephalus chinensis (Lamk) A. Rich. ex Walp.). In Papua New Guinea and New Britain, O. sumatrana is occurs in habitats similar to those of kamarere (Eucalyptus deglupta Blume) with which it is sometimes associated. The riverine O. sumatrana forest is usually characterised by good drainage and only temporary flooding. The most important condition for growth of O. sumatrana appears to be an evenly distributed annual rainfall of at least 1500 mm.
Line Drawing / Photograph
References
1. Plant Resources of South-East Asia No. 5(2): Timber trees: Minor commercial timbers
