ABOVE: Ficus caulocarpa in full fruit at Tg Aru beach. The five species of Section Urostigma strangling figs found in Borneo produce a spectacular abundance of figs on their branches (ramiflorus) when fruiting. Only two species of Section Urostigma figs are relatively common in Borneo, F. virens and Ficus caulocarpa. They are distinguished by differences in their leaves. See below.
CAULOCARPA Ficus caulocarpa Miq. (1837) SECTION: UROSTIGMA
Latin: Stalked fruit presumably referring to peduncle (stalk) of the fig fruits. Many fig fruits do not have a stalk and are attached directly to the twig.
Habit: Large strangler (to 35 m) found throughout lowland Borneo including both town parks and primary forest. Often produces numerous aerial roots which establish in a tight bunch next to the main trunk (see below) unlike Ficus microcarpa where the aerial roots often establish away from the main trunk giving a banyan type appearance.
Sex: Monoecious (bisexual).
Fig fruits: The tiny figs (0.3-0.5 cm) are ramiflorus and grow on old wood grow in dense crowds along the smaller branches and twigs. Figs ripen white with pink spots, later turning dull purple.
Ecology: Typically tiny figs only attract small sized dispersers such as bulbuls and squirrels but Caulocarpa fig crops are produced in such overwhelming abundance that they attract the largest fig eaters such as Rhinoceros Hornbills and Orangutans as well as small birds.
Distinguish: Can be distinguished by the fallen leaves which are a distinctive oblong shape with a clearly marked “hinge” at the junction of the blade (lamina) and the stalk (petiole). The main leaf vein, the leaf stalk, the bark and the dangling roots are often (but not always) reddish brown.
Similar species: Ficus virens which has similar habits and is also in Section Urostigma.
Both species are common large stranglers which often grow as very large independent trees. Both species are generalist in habits found both in towns and in primary forests. Both species produce large numbers of tiny ramiflorus figs which ripen white with pink or purple spots. The main distinguishing feature is the shape of the leaf which is long and oblong in F. caulocarpa with a long reddish petiole (leaf stalk). See below
F. virens leaf is a smaller more normal leaf shape with a shorter petiole that is pale green rather than reddish. Overall in Borneo both species are common both in towns and open countryside as well as virgin primary forest.
Distribution: Common in lowland forests including Poring, Danum and Maliau in Sabah. There are several large individuals at Tg Aru beach, Kota Kinabalu. In Brunei common both in coastal and hill forest. In Kalimantan found recorded at Sungei Wain and on Pulau Maratua.
Range: Sri Lanka east to Taiwan and south to New Guinea. An uncommon coastal fig tree in Singapore.
Typical leaves of Ficus caulocarpa (from Maratua)
Ficus caulocarpa growing at Tanjung Aru beach, Kota Kinabalu. Note the size of the car.