Overview: Earth Figs of Borneo

Photo above: Earth Fig  Ficus megaleia  (male fig fruits) growing at Sapulot in Sabah. Earth fig fruits typically grow at ground level on root like stolons that grow from the base of the fig tree trunk. The fig fruits are often covered by leaf litter and may be difficult to find. Photo by Anthea Phillipps. 

Earth Fig Leaves  typically are very large, soft and  slightly hairy with toothed (dentate) edges. Often the base  of the leaf is lobed on one side (decurrent) . The leaves of young plants which often grow by the roadside in wet areas are usually much bigger than the leaves of adult trees. The photo above shows the leaves of Ficus malayana near the entrance to the Kinabalu Mountain Garden at Kinabalu Park HQ.

 

HOW TO DISTINGUISH THE 11 DIFFERENT EARTH FIGS IN BORNEO

For photos of individual species see the links below

Ten different species of earth figs occur in Borneo in Section SYCOCARPUS. They are all dioecious with separate female and male plants. The two sexes look similar and can only be distinguished by their ripe fruit. Note that only female figs produce seeds and male figs only produce fig wasps.

Earth figs are common in wet forested areas of Borneo, often growing along roadsides. They are distinguished by their very large, often asymmetric, hairy leaves (which are never opposite). To confirm the ID, search at ground level for long root like stolons emerging from the base of the plant with curious dark crimson fruit covered in large bracts.

1.  F. megaleia: Large dentate leaves with uneven lobed base. 6-24 pairs of side veins not 6-7 pairs (malayana). Male fig has dark crimson glaborous flat bracts which overlap like the scales of a snake not upstanding and hooked like F. malayana.    Ficus megaleia, Sapulot, Sabah
2. F. geocharis Oblong entire leaves which are symmetrical apart from a very distinctive auricle or “ear” at the leaf base .Ficus geocharis, Kipandi, Crocker Range, Sabah
3. F. bukitrayaensis: Large dentate,  asymmetrical leaves with uneven lobed base-similar to Ficus megaleia. Figs glaborous covered with hairs only when immature. Figs with poorly formed soft uneven bracts. Figs ripen pale pink to white or green. Ficus bukitrayaensis, Tongod, Sabah
4. F. stolonifera: Leaf dentate and hairy. Base only slightly uneven. Few bracts on the figs. Soft reddish figs often with white spots, sometimes on long stolons hanging high on the trunk but reaching the ground. Probably related to F. ribes, see below: Ficus stolonifera
5. F. subterranea : Leaf entire and symmetrical. Leaf glaborous (not hairy). No auricle. Normal drip tip.Ficus subterranea, Crocker Range, Sabah
6. F .beccarii: Leaves entire symmetrical, narrow, with very long drip tips.Ficus beccarii: Introduction
7. F. uncinata: Leaf dentate with distinctly uneven lobed base.  3 -7 pairs of side veins. Fig brown densely hairy with hooked bracts.  NOT FOUND IN SABAH. Ficus uncinata, Ulu Ulu Resort, Temburong, Brunei
8. F. malayana:  Leaf dentate with uneven lobed base. Only 3-7 side veins. Bracts on fig thick and strongly hooked. Figs usually ripen bright red/scarlet with sparse hairs when immature. THE MOST COMMON EARTH FIG IN SABAH. Especially common on Kinabalu around the Park HQ  and along the roadside of the roads that cross the Crocker Range. Ficus malayana, Kinabalu Mountain Garden
9. F. temburongensis. This very unusual rare earth fig has leaves  similar to Ficus lepicarpa which are  entire, glaborous (shiny)  with 7-8  slightly sunken side veins. The leaves grow in whorls at the ends of the branches and have silky hairs on the upper surface as with F. cereicarpa and F. francisci. The fig fruit however look like typical earth figs e.g. F. malayana or F. uncinata.  All the other earth figs have leaves which grow in flat planes in two opposite rows (distichous). Ficus temburongensis: Introduction.     
10. F. ribes: An unusual earth fig, small, bright red with white spots. Locally common on Java and the Malay Peninsula but not recorded by Berg for Borneo. Recent discoveries at Mesilau and in the Crocker Range. Ficus ribes at Mesilau.
11. Ficus treubii: Typically, the small greenish grey figs hang on strings from the lower branches of the small tree like a beaded curtain. The figs may also grow on stolons at ground level over the surface of the ground. Ficus treubii: Introduction

 Taxonomic Notes: The taxonomy of Borneo’s earth figs was originally summarised by Corner in Berg (2005). This treatment was later revised by Berg et al (2007) in A study of the taxonomy of some stoloniferous species of ficus subsection sycocarpus (Moraceae) in Thailand and Malesia. On this website  for earth figs we follow Berg (2007). 

Berg (2007) New species of earth figs Borneo and Thailand

However it is obvious that the vast variety of the 11 different earth figs found in Borneo do not fit easily into such a rigid framework. In particular;

1. It is likely that some earth figs with very large leaves may actually be the juvenile forms of other species (differences in adult and juvenile leaves are very common in the Moraceae plant family) and
2.  There appear to be intergrades between some species (perhaps hybrids) – particularly F. megaleia, F. uncinata and F. bukitrayensis which all produce very similar large hairy, dentate leaves with asymmetrical bases as juvenile plants. In adult trees the leaves are different again, so the written descriptions given above may not be sufficiently clear cut to identify some individuals.
3. The earth fig labelled as F. malayana by Berg(2007) was previously called Ficus uncinata by Berg (2005) and vice versa. Very confusing !  Note that according to Berg Ficus malayana  is found throughout Borneo and the Malay peninsula whilst F. uncinata is endemic to southern Borneo and is not found north of the Sarawak border with Sabah.
4. This means that the common earth fig at Kinabalu Park HQ is  Ficus malayana NOT  Ficus uncinta. 

Dispersal: Earth figs are probably dispersed by ground mammals such as treeshrews, rats, porcupines, deer, pigs and sun bears.

Edible by Humans: Ripe earth figs are considered by locals to be delicious

Seed Predation: The bracts or hairs covering the fig fruits are believed to have evolved to prevent ground birds such as partridges and pheasants from swallowing the figs whole. Toothless ground birds use grit filled gizzards to grind up small seeds and are therefore potential seed predators of earth figs. The seeds of figs that grow at ground level in Borneo are tiny, only half the size of the seeds of  most bird dispersed figs. This indicates higher predation pressure of ground level figs compared with canopy figs.

Variation: The  tendency for morphological variation in earth fig leaves and earth fig fruits indicates lower dispersal distances (both of seeds and fig wasps)  compared with bird  and bat dispersed figs in Borneo.

Probably this is the result of both genetic drift  and differences in seed predator pressure on relatively isolated earth fig populations. However  variations in the DNA of  Borneo’s earth fig populations has yet to be studied.

EARTH FIG GLOSSARY:

Asymmetric: Leaf shape is uneven usually with a large lobe on one side at the base of the leaf

Dentate: Toothed edge to leaf

Entire: Smooth edge to leaf

Glaborous: Smooth/shiny with no hairs or sparse hairs

Stolon: Root like “runners” or strings usually produced from the base of the trunk sometimes higher up with figs growing at intervals along the stolon. Stolons  may also root to the ground.