ABOVE: Ficus opposita from the online catalog of DaleysFruit.com.au based in Kyogle northern New South Wales, Australia
Ficus opposita is a common large bush or small tree found in secondary and coastal forest from New Guinea south to Northern Australia. The scientific name derives from the fact that the leaves are often opposite on the twig a very unusual arrangement for a fig. Illustration from www.plantillustrations.org
Ficus opposita is unusual in another way as well. All figs in Section Sycidium are dioecious i.e. separate male and female trees. Female trees produce fruit with seeds whilst the figs on male trees are used as breeding sites for pollinating fig wasps. Whilst ripe male and female figs can be told apart from external appearance, normally the plants cannot. However this by article by Greg Calvert Calvert (1998) Ficus opposita Queensland claims that male and female Ficus opposita trees can be told apart by appearance.
See also this article by Dale Dixon regarding the Ficus opposita species complex in Australia. Dixon (2007) Revision of the ficus opposita complex Australia
Ficus opposita has not yet been recorded from Borneo and is included on this Borneo fig website for three reasons;
(1) According to Berg (2005) F. opposita is very closely related to F. cumingii. F. cumingii is a common fig of the Philippine Islands with additional records from Tawau in E. Sabah (Borneo) and N. Sulawesi. See map below.
(2) F. opposita is used by humans for multiple purposes and therefore might well be transported outside the native range and cultivated elsewhere. The leaves can be eaten as a vegetable, the ripe figs apparently taste delicious and the stringy bark is used to make rope.
(3) F. opposita is one of a few figs which can be used as a root stock for growing the Edible Fig, Ficus carica in very wet tropical climates such as Borneo. See these posts by Craig Hepworth Florida Fruit Geek.
This distribution map by E J H Corner copied from Berg (2005)shows a very unusual record from Pulau Sangiang well away from the normal range.