Saturday, May 28, 2011
A fascinating tree found in the tropical hammock areas of south Florida is the strangler fig. It is a member of the fig genus, which in turn belongs to the mulberry family (Moraceae). The common name comes from its frequent habit of germinating in the tops of trees, sending encircling roots down along the trunk of its “host,” which usually results in the death of the original tree.
Strangler fig is not a true parasite as many people think. It starts life when a bird eats the fruit and then eliminates the seeds, usually from a perch high above the ground. The seed lodges in a crevice of rough bark, the crotch of a tree, or in the base of the fronds of a palm tree. After germination, the seedling lives on nutrients and water from the air while it sends aerial roots to the forest floor; it does not take any sustenance from the host tree.
Once the roots can take up water and minerals from the soil below, it grows further, competing with the host tree for sunlight and nutrients. The roots enlarge and often encircle the host tree, preventing it from growing. The host tree often dies later, shaded out by the fig’s canopy of leaves, and weakened by the growth of its roots. Strangler figs will also germinate in the soil, developing a conventional trunk, and can grow to 50 feet high.
The shade of its broad crown is welcome on our hot Florida summer days, its canopy composed of distinctive deep green leaves with a pale midrib. The color of the fruit inspired the scientific name of Ficus aurea (Golden Fig). The yellow to sometimes reddish-purple fruit is valuable to birds and other wildlife, and are reportedly edible for humans as well. The milky sap contains latex, which was used historically as a chewing gum – but is also a skin irritant for many people. The elliptical to oblong leaves are the larval food of the ruddy daggerwing butterfly.
The fruits of the fig family are unusual: the inflorescence is turned inwards inside of the “berry.” In other words, the inside of the fruit contains tiny flowers that grow on the inside, toward the center. This presents a problem for normal pollinators, but a tiny wasp has developed a relationship with the fig family. You can read more about this relationship here.