Ficus crassiramea is one of the most common large stranglers found in lowland forests of Borneo including peat swamp, coastal forest and islands.
In virgin hill forest F. crassiramea is replaced by a close relative the giant forest strangler Ficus stupenda with much larger leaves and much larger figs.
Ficus crassiramea tends to intermittent seasonal growth flushing with new leaves in one big bang.
These new “big bang” leaves are initially covered by extra large colorful “flushing stipules” in a dramatic display.
The photos below show both normal stipules and flushing stipules on the same Ficus crassiramea fig tree.
Other fig species that produce flushing stipules in Borneo include Ficus subgelderii, Ficus acamptophylla, Ficus virens, Ficus caulocarpa and sometimes Ficus annulata and Ficus globosa.
The ecological reason for the dramatic display of flushing stipules is currently unknown.
A possible explanation is that soft tasty young fig leaves are prone to attack by many insects including the larvae (caterpillars) of many moths and butterflies.
The adult insects mostly fly at night and detect new leaves by scent (rather than sight) and lay their eggs on the young leaves .
The bright colours of the flushing stipules maybe an advertisement during daylight to passing insectivorous birds indicating that a feast of young caterpillars awaits.
My hypothesis is therefore that the purpose of flushing stipules is to protect new leaves against folivorous insects.
Thanks to Ripin for information and photographs.
