Edible figs (Ficus carica) belong to the Moraceae (mulberry) family, and the genus Ficus is one of the largest of the angiosperms (flowering plants) with over 800 species, characterised by their milky latex and their uniquely structure of its fruit, known as figs, which are actually inverted flowers, with hundreds of flowers and seeds contained inside a fleshy, succulent, hollow receptacle (known as a syconium).
The common fig, Ficus carica, is native to the Mediterranean region, and the area extending from Asiatic Turkey to northern India and was brought into cultivation in the southern Arabian Peninsula by 3000 BC. It’s the most important commercial Ficus species because it produces edible fruits and is one of the earliest fruit trees to be cultivated, found in excavations of Neolithic sites tracing back to at least 5,000 BC.
What Are Fig Tree Main and Breba Crops?
Fig trees are quite prolific fruiting trees, and many varieties may produce two crops per year.
- The first crop, also known as the breba crop, is an early crop that’s produced on the tips of the previous season’s growth (year-old wood) during the spring season. These early fruits ripen in late spring to early summer (May-June in the Northern Hemisphere, November-December in the Southern Hemisphere), and usually mature earlier than the main crop and are generally being larger than the main crop as they have longer to ripen but are often less abundant in quantity.
- The second crop is known as the main crop, is a larger and more significant crop of figs that’s produced at the base of the current season’s growth, which is harvested in late summer to autumn. After the breba crop is harvested or matures, new growth emerges, and the main crop of figs form on these current season’s branches. These figs usually take longer to mature, and this crop is generally more abundant then the breba crop.
This dual cropping nature means of fig trees means that they have special pruning requirements, as cutting back all branches will cause the complete loss of the breba crop. Instructions for the correct way to prune fig trees can be found in the article – Fruit Trees with Special Pruning Requirements – Figs, Persimmons and Pomegranates
Do Fig Trees Need Wasps to Pollinate Them?
Common edible figs (Ficus carica) are parthenocarpic (from Greek parthenos virgin + karpos fruit), meaning they can produce fruit without pollination, and do not need to be pollinated by fig wasps or any other insects. The reason they don’t need pollination is because they have either been bred to be self-pollinating, or have been selected from natural varieties that can produce fruit without pollination.
So why do we hear about wasps needing to go inside of figs to pollinate them?
The reproductive biology of figs is very complex, and there are some fig varieties which do need pollination.
Fig trees are gynodioecious, which means that some varieties of fig trees bear female flowers only, while other varieties bear hermaphrodite flowers only, that have male and female reproductive organs within the same flower.
Only the female flowering fig varieties, which are known as the fig types produce fruit that are palatable to humans. The hermaphrodite flowering varieties are known as the caprifig types and produce fruit that are inedible to us.
Even though the caprifig type trees bear male and female flowers (hermaphroditic), they’re functionally male fig trees because they produce pollen but don’t yield edible fruits, but are necessary to pollinate some of the female fig type varieties via caprification (pollination), which is carried out by fig wasps or can be done manually.
Edible fig varieties, all of which bear only female flowers, can be classified under three main groups, based on their reproduction biology and pollination requirements:
- Common type, which develop fruits parthenocarpically, and can produce both a breba crop and a main crop.
- Smyrna type, which are non-parthenocarpic, and require pollination to bear the main crop but do not usually produce a breba crop.
- San Pedro type, which produce a breba crop parthenocarpically, and a main crop generally after caprification (pollination) or even parthenocarpically.
What Is Caprification and Why Is It Important for Fig Pollination?
Caprification is the artificial pollination of figs that is carried out by hanging male flowering branches of the caprifig in the trees to facilitate pollen transfer by fig wasps (Blastophaga spp., such as Blastophaga psenes).
The fig wasp Blastophaga psenes is a very tiny, shiny black wasp around 2mm (0.079 in) long with very thin, transparent wings, while the males are smaller and wingless.
Figs that do require pollination have a unique pollination process that involves a mutualistic relationship with these fig wasps, where both the fig tree and the fig wasp benefit from it.
In biology, mutualism can be defined as a symbiotic relationship between organisms of different species in which both individuals benefit from the association, and in some cases, totally rely on one another for survival.
The wasps carry pollen from male flowers of the inedible caprifig fruits to the female flowers of the edible figs in the main crop.
The pollination process works as follows:
- After the female fig wasps emerge from the caprifigs, they enter the cultivated fig fruit through the small opening at the bottom of the figs, which is known as the ostiole.
- When the wasps enter inside the figs, they inadvertently pollinate the female flowers of the cultivated fig tree, and also lay their eggs in some of them.
- After pollination, the female wasps eventually die inside the figs.
- The pollination of the cultivated fig flowers triggers the development of the fruit. The seeds within the fruit develop from the fertilized female flowers, and the figs grow and ripen around them. The wasp eggs hatch and the wasp larvae that emerge feed on some of the developing seeds, providing them with nutrients to grow and develop.
This pollination process occurs naturally where caprifig trees grow, but caprification by growers has been practiced in the Mediterranean area for centuries, and is documented by Aristotle, Theophrastus, and Pliny the Elder.
The practice has fallen out of favour because collecting fruiting caprifig branches and putting them in the cultivated tress is a laborious and costly process. As a result, self-fertile fig varieties that don’t require pollination have been selected for commercial production and for growing home gardens.
What this means is that any commercial figs that people can buy won’t have dead wasps in them!
Even with the figs that are pollinated by wasps, nature has been kind to us. Figs contain the enzyme ficin, which is a proteolytic enzyme that can break down proteins into their building blocks, amino acids. This enzyme is effective in digesting animal proteins such as wasp bodies, so by the time the figs are ripe to eat, the wasp bodies will be long gone!
If commercial varieties of fig trees, which most people grow, aren’t producing fruit, it’s not because they need pollination.
More often, it’s because the fig trees:
- Need a fertiliser which contains potassium (potash) to supports flowering and fruiting
- Are affected by frosts or freezing temperatures which can damage or kill the fruit buds and developing figs
- Are suffering drought stress due to insufficient water
- Lack of sunlight due to growing in shaded areas or overcrowded conditions which can lead to reduced fruit production or poor fruit quality.
Another common cause is a climatic shift where summers are abnormally short, so the figs don’t receive sufficient warm weather to grow and ripen.
References
- Manuel Ayuso, Maria Carpena, Oludemi Taofiq, Tânia Gonçalves Albuquerque, Jesus Simal-Gandara, M. Beatriz P.P. Oliveira, Miguel A. Prieto, Isabel C.F.R. Ferreira, Lillian Barros, Fig “Ficus carica L.” and its by-products: A decade evidence of their health-promoting benefits towards the development of novel food formulations, Trends in Food Science & Technology, Volume 127, 2022, Pages 1-13, ISSN 0924-2244, https://doi.org/10.1016/j.tifs.2022.06.010. <https://www.sciencedirect.com/science/article/pii/S0924224422002035>
- Marcotuli Ilaria, Mazzeo Andrea, Colasuonno Pasqualina, Terzano Roberto, Nigro Domenica, Porfido Carlo, Tarantino Annalisa, Aiese Cigliano Riccardo, Sanseverino Walter, Gadaleta Agata, Ferrara Giuseppe. Fruit Development in Ficus carica L.: Morphological and Genetic Approaches to Fig Buds for an Evolution from Monoecy Toward Dioecy. Frontiers in Plant Science, Volume 11, 2020. DOI 10.3389/fpls.2020.01208, ISSN 1664-462X <https://www.frontiersin.org/articles/10.3389/fpls.2020.01208>
- Britannica, T. Editors of Encyclopaedia (2023, April 11). Ficus. Encyclopedia Britannica. <https://www.britannica.com/plant/Ficus>
- Ficus carica (common fig) | CABI Compendium. Cabi digital library. <https://www.cabidigitallibrary.org/doi/10.1079/cabicompendium.24078>
- Dani Moore. (2012, October 11). Figs Without Wasps? ASU – Ask A Biologist. Retrieved May 26, 2023 < https://askabiologist.asu.edu/figs-without-wasps>
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