RUBBER FIG Ficus elastica Roxb (1814 SECTION: CONOSYCEAE
Latin: Elastic referring to the rubbery latex
Habit: Large strangler or independent tree not native to Borneo but often planted as an ornamental tree in parks and towns. A very common house /office/shopping centre plant known as the Rubber Tree throughout the world. Note that although F. elastica has been cultivated for rubber in the past, all natural rubber is currently harvested from plantation trees of Hevea braziliensis (Euphorbiacea family) originally from Brazil,
Leaves: The large leaves are thick and leathery. The leaves are distinctively “penniveined” meaning that veins are tightly packed in parallel rows. This matches the leaves of a number of Bornean figs including F. callophylla and F. glandifera. The stipules are very long and pointed and are normally coloured bright pink or reddish
Fig: The figs are oblong and ripen green to reddish. The immature figs are covered in “calyptrate bud covers” like petals which fall off as the fig grows in size, leaving the mature fig fruit supported on a very thick peduncle (fruit stalk) almost the same width as the fig fruit.
Similar species: Ficus glandifera, F. callophylla which both have large penniveined leaves.
- Ficus glandifera figs sit in a cup like an acorn not on a stalk or peduncle.
- The ostiole of Ficus glandifera is more of a slit then a hole.
- Ficus callophylla figs do not sit in a cup.
Taxonomy: Berg and Corner (2005) created a new section Stilpnophyllum which placed F. elastica in the same grouping as the Australian stranglers belonging to Section Malvanthera but this theory was demolished by Ronsted et al in a series of papers. Currently Ficus elastica is considered to belong in Section Conosycea which includes most of the hemi-epiphytic stanglers.
Distribution: Introduced Ficus elastica is commonly planted in towns and surrounding areas in Borneo. Although individual trees in Kota Kinabalu may produce figs, no young plants have yet been recorded and it is likely that these figs are sterile because of a lack of pollinating wasps. This means that F. elastica is unable to establish in the wild in Borneo.
However fertile figs and pollinating fig wasps have recently been recorded in Singapore for the first time. Harrison (2017) Pollination of Ficus elastica in Singapore
Range: NE India to northern Malaya, Sumatra and Java. Introduced and planted elsewhere. Berg (2005). In the wild normally associated with limestone hills.
Ficus elastica and the Rubber Industry: The first submarine telegraph cables (1850’s) were covered with the waterproof rubbery latex of Dyera consulata (jelutong or gutta-percha) a common forest tree in Borneo, but industrial demand soon exhausted the forest supply. The growth of the car industry at the end of the 19th Century stimulated the establishment of many experimental plantations of latex producing plants in SE Asia and S. America including Ficus elastica plantations.
However, the industries that used rubber for tyres and waterproofing reported that the best rubber was produced by a tree found wild in the Brazilian jungle Hevea braziliensis. Once Hevea plantations came into production in Malaya, as a result of the work of Henry Ridley of the Singapore Botanic Garden the Ficus elastica plantations were abandoned.