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Living Sanibel: The strangler fig is one of the most important plants in SW Florida

By Staff | Apr 5, 2017

Strangler fig. Charles Sobczak

Considered by many botanists to be one of the most fascinating plants on earth, the strangler fig is also one of the most important plants in Southwest Florida. Worldwide there are more than 900 species of the fig tree, with most occurring in the Australasian region. One species (Ficus bengalensis), native to India, has a trunk that measures more than 100 feet in circumference. The century-old banyan fig planted at the Edison and Ford Winter Estates in Fort Myers covers an acre and is well worth visiting (see edisonfordwinterestates.org for hours, information and directions).

Throughout its range, the strangler fig is one of a handful of plants that form a virtual breadbasket for wildlife. The small, good-tasting figs produced by this tree are eaten by almost everything, be it a flying, crawling, or a climbing creature. The fruit of the strangler fig was used for food by the early Floridians as well.

This is a favorite shelter tree for birds, from warblers to pileated woodpeckers. Its niches, twisted trunks, and nooks and crannies of the strangler fig also provides habitat for insects, lizards, raccoons, rodents, and snakes.

The reproductive cycle of the strangler fig is so bizarre that it demands telling. It has a relationship, scientifically referred to as obligate mutualism, with a single wasp species known as the gall wasp. This wasp is only slightly larger than a no-see-um, and each fig has a tiny hole, just large enough for a female gall wasp, full of eggs, to squeeze into. Its delicate wings are torn off in the process, and the wasp is unable to leave. It unknowingly deposits the pollen that it has carried from another tree and lays its eggs in the stigma of the flowers located within the fig seed.

The female then dies, and the entrance it came through seals shut as the fig walls close. After a while, the larval wasps are born. After mating, the males chew a hole in the wall of the fig, crawl out, and die. The females remain inside the fig, collecting pollen in preparation for their own escape. The females are born with delicate wings capable of making a single flight. If the female gall wasp fails to find a tree before its fragile wings fail, it dies. If she finds another tree, her life cycle is completed, and the strangler fig’s flowers are pollinated. It’s believed that this evolutionary codependency has been going strong for 60 million years and that there are hundreds of different species of fig wasps matched to hundreds of specific fig species.

As if this unbelievable symbiotic relationship weren’t enough, the story of the strangler fig continues. Once pollinated, these figs ripen and are fed upon by a host of hungry wildlife. The fruit is packed with tiny seeds, passed in the dung of various animals. In Southwest Florida, birds are responsible for most of the seed dispersion.

After feeding, a bird might land in a cabbage palm and dispose of its waste. That waste is often trapped in the upturned bases of the palm fronds, where detritus and standing water allow the tiny seeds to germinate. At this stage in its development the strangler fig survives as an epiphyte. As this epiphyte matures it sends down long, thin tendrils that eventually reach the soil near the base of the host tree. With the newfound nutrients in the soil now feeding it, the strangler fig grows rapidly. Its tendrils twist and turn, eventually wrapping themselves around the trunk of the host tree, which is generally a cabbage palm. Over time the fig grows so large that the cabbage palm no longer receives enough sun to survive. Eventually, the host tree and its root ball decay into nutrients that help to make the mature strangler fig the largest native plant in South Florida.

In one last amazing feat of adaptation, the strangler fig’s limbs are designed with a breakaway system that allows it to survive hurricanes. The leaves are the first to let go, with the branches quick to follow. This system allows the base of the tree to survive and flourish soon after the storm has passed. If the storm is so strong that it takes down the trunk, the root suckers left buried in the soil will generate a new sapling. The strangler fig is salt tolerant, which makes it resistant to storm surges as well. All said, the strangler fig is a true survivor.

This is an excerpt from Living Sanibel – A Nature Guide to Sanibel & Captiva Islands by Charles Sobczak. The book is available at all the Island bookstores, Baileys, Jerry’s and your favorite online sites.