Common Name: Strangler Fig
Latin Name: Ficus ssp.
Family: Moraceae, the fig/mulberry family


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Fig. 1: Strangler fig in La Selva Biological Station in Costa Rica


Range: Strangler Fig species grow in tropical rainforests worldwide.
Abundance: common
Coloration and Morphology: Strangler Fig trees have light colored bark with umbrella shaped canopies. They can grow up to 148 meters tall. They have simple, alternate leaves that are ovoid in shape with drip tips and a waxy texture to cope with the tropical environment (drip tips prevent them from getting too wet and the wax protects them from drying out). The leaves are green, darker on top and lighter below. They produce fruits called figs, which are green on the outside with red or pink coloring in the middle surrounded by light coloring on the inside.


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Fig. 2: Fig fruit split open.



Reproductive cycle: Strangler Figs are angiosperms, meaning they bear fruit and flowers.

Habitat: tropical rainforest, canopy

Ecology: Strangler Figs are considered to be a keystone species in the tropical forest because they produce fruit frequently. Different species produce fruit at different times of the year so there is virtually an endless supply of figs for different species to eat.

Behavior: The most interesting thing about Strangler Figs is their behavior. Strangler Figs are what is called hemi-epiphytes. This means that they start their lives as epiphytes – their seeds are dispersed via animal droppings into trees where they begin to grow – but end their lives with roots anchored into the ground like what most people think of as the typical tree. This strategy is unique and successful because it makes it so they do not have to cope with the poor soils of the tropics, instead of developing root adaptations to try and draw out more nutrients they get their nutrients (and water) from what builds up in the nooks of the host tree. Once they have begun to grow as epiphytes they then drop down aerial roots that anchor into the soil once they reach the ground. At this point the Strangler Fig goes through a growth spurt and begins to suck up a lot of nutrients from the soil. Additionally they produce more leaves in the canopy and take in a lot more sunlight. Both of these occurrences create competition with their host tree. The Strangler Figs are depleting nutrients in the soil for the host to use, and they are blocking out sunlight. Eventually, the Strangler Fig ends up killing their host tree both by outcompeting them and by physically constraining the host tree from growth widthwise with their roots which twist down the trunk of the host tree – this is why they get the name “strangler”!

Interactions with other Species: Strangler Figs have a symbiotic relationship with aganoid wasps (in the order Hymenoptera and the genus Agaoninae). The female aganoid wasps enter the hollow fruit-bearing structure, called the syconia, then the males fly from tree to tree mating with the females and in doing so they pollinate the trees. The females lay their eggs within the syconia and they are fed by the tree, so they benefit from the relationship just as much as the Figs do. These species exchange shelter and food for pollination.

Personal Experience: We observed several Strangler Figs in La Selva, Costa Rica in varying stages of their life cycle. There were some Stranglers who were still in the stage of dropping aerial roots and then there were also some that were quite large and wrapped around their host with canopies that were out-competing the host for light. We did not, however, observe any Strangler Figs that had completely killed their host tree yet.

References:
“Seed Germination and Seedlin Distribution of Ficus pertusa and F. tuerckheimii: Are Strangler Figs Autotoxic?” Biotropica, 22(4): 425-428. 1990.
http://www.blueplanentbiomes.org/strangler_figs.htm Viewed on 2-11-12