A Ficus densechini spiny liana stem photographed at Sayap Station on the very wet western slopes of Kinabalu Park, Sabah.
Chun Xing WONG to show the scale.
The hill forest at Sayap is extremely rich in figs including root climbing figs such as Ficus allutacea, Ficus grandiflora, Ficus carrii and Ficus densechini and strangling figs with drop down aerial roots such as Ficus stupenda and Ficus borneensis.
In addition there are forest fig trees such as Ficus nervosa, and riverine figs such as Ficus lepicarpa, Ficus rubrocuspidata and Ficus leptocalama.
In most of Borneo rain normally falls once a day. At Sayap rain normally falls twice a day.
As a result almost every old tree is covered in moss, root climbing plants, epiphytes and lianas.
Fortunately, the spines on the liana stem of Ficus densechini makes it easy to distinguish.
The spiny liana stem shown in the photograph is NOT a drop down aerial root originating from the canopy above but the original root climbing liana stem which started from a seed in the ground and used its sticky roots to climb slowly up the nearby tree trunk. Once the root climbing liana reached the sunlight of the canopy, F. densechini put out leafy side branches to harvest sunlight. At the same time the fig leaves on the liana next to the host trunk were dropped and the originally liana tensioned and constricted. This pulled the liana away from the host trunk and turned it into a rigid support for the original old host tree .
In evolutionary terms what are the possible explanations why Ficus densechini evolved this growth strategy;
Two suggestions which are not mutually exclusive;
- Ficus densechini is unlikely ever to become self supporting but the now rigid F. densechini trunk might allow the host tree to survive longer than it would otherwise. Once the host dies and rots away, F. densechini will die.
- F. densechini produces very large brown figs. The only possible dispersers for these figs once they are ripe are primates such as gibbons and orangutans and also civets. The now rigid liana, away from the main trunk provides an easy climbing rope to access the ripe figs.
- Another root climbing fig, Ficus punctata which also produces very large figs has a similar growth strategy. See Ficus punctata at Tawau Hills.
