Pollination of Fig Trees

Overview

Figs (Ficus spp.) comprise some 500 to 800 species of trees and shrubs native to the tropics. Perhaps the most important is the edible or "common" fig (Ficus carica), a subtropical tree that yields tasty fig fruits. There are hundreds of cultivars of common figs, some with distinctly flavored or sized fruits and some better adapted to different, adverse garden conditions. Other species of fig trees are popular as massive shade trees in parks and gardens and their fig fruits are relished by wildlife.

Fig Flower Features

While the fig is considered a flowering plant (angiosperm), they are not showy or readily displayed like other garden flowers. Fig flowers develop directly on the branches, described botanically as cauliflorous. Blooms lack petals and are enclosed inside a fleshy receptacle called a syconium. Depending on species of fig, different gendered syconia are produced on different trees or in some types both male and female organs occur in the same syconium, according to Wayne's Word and "Tropical Flowering Plants."

The Syconium

To the human eye, a fig flower looks like a tiny, immature fig fruit. Technically, the syconium is the flower and the fruit of the fig tree. According to Wayne's Word, a ripe syconium (what we call a fig fruit) is a fleshy, flask-shaped, modified stem lined on the inside with many tiny, one-seeded fruits (drupelets) and, therefore, not a true botanical fruit. At the far end of the syconium is a tiny opening called an ostiole. The syconium's hollow core is lined with tiny male stamens or female pistil organs. Once female pistils are pollinated, their ovaries enlarge and the syconium wall becomes fleshy and sweet.

Insect Pollination

Each species of fig tree is pollinated by a specific species of gall-wasp, according to Kirsten Albrecht Llamas, author of "Tropical Flowering Plants." The female wasp travels into the fig syconium via the ostiole and fumbles around inside it. As the female wasp enters and exits various syconia on the tree, she transfers male pollen onto the female pistils, facilitating fertilization.

Parthenocarpy

Some species of fig trees, including many modern cultivars of common figs, will develop their syconia into fleshy fruits without pollination or fertilization, a situation known botanically as parthenocarpy. Thus, the tiny gall-wasp is not needed to form fig fruits, although no seeds are produced if pollination doesn't occur. In some species of fig trees, if female syconia are not pollinated by gall-wasps, they simply abort and drop off the tree, according to Wayne's Word.

Common Fig Types

In the case of the common fig, there are different types of plants that produce syconia with different compositions of sex organs. Some types have both sexes in each syconium, others in different syconium on the same plant, others on completely separate trees. According to Purdue University, there are other types called "Caprifig," 'Smyrna" and "San Pedro-type." Caprifigs require a gall-wasp to ensure pollination and development of fruits. Smyrna fig plants require cross-pollination from wasps that carry pollen from Caprifig plants. San Pedro-types typically produce a first "flowering" that develops into fruits via parthenocarpy and then a later-season "flowering" that produces fruits only if gall-wasp pollination occurs. Purdue University says that most garden-grown common figs are regarded as "independent," as they produce their fruits from parthenocarpy.

Keywords: fig tree pollination, fig fruit production, Ficus, parthenocarpy

About this Author

James Burghardt became a full-time writer in 2008 with articles appearing on Web sites like eHow and GardenGuides. He's gardened and worked professionally at gardens in Colorado, Florida, Minnesota, New York, North Carolina and Pennsylvania. He holds a graduate diploma in environmental horticulture from the University of Melbourne, Australia and a Master of Science in public horticulture from the University of Delaware.