Strangler figs, essential trees

You won't believe it when you come face to face with a strangler fig, but they're in the same genus as the Ficus we find in the little flowerpots of our homes. You'll recognize the shape and color of the leaves. A veritable larder for the forest and fruit-eating animals, over 1,200 species feed on figs throughout the year. Its importance is therefore essential. Ficus can be found in most Costa Rican forests up to 1800m altitude. It is easily observed in Rincon de la Vieja, Arenal, Corcovado or even Monteverde. There are over 750 types of fig tree in the world. Gigantic ones can be found, some with hollow trunks. But how is this possible?

The Strangler Fig, a tree that lives at another's expense

To better understand the "strangulation" phenomenon of ficus, we need to talk about its roots. The strangler fig is a hemiepiphytic tree, meaning that it is able to live epiphytically (growing on a medium other than soil) for part of its life cycle. Let's explain the process in a little more detail.

Fig tree growth

A seed is eaten by a bird. It emits an excrement and this falls on a high branch. This seed will give rise to leaves which, like most other plants, will collect light rays in order to carry out the growth of the plant. photosynthesis. And so-called aerial roots. These go, by gravity, grow towards the ground. Once the soil has been reached, the plant can feed on its nutrients. The aerial root will then, still anchored in the area where it first touched the ground, grow by gradually sticking to the trunk of the tree on which the seed was deposited. Once the host trunk is reached, a veritable network of roots adheres to the trunk. These roots then grow in thickness until they touch each other. In some cases, these roots will fuse together to form a larger root. The fig tree thus becomes a self-supporting tree and no longer needs the support on which it grew to sustain itself. In contrast, the branches and leaves of the Strangler Fig will grow to the top. Strangler figs have very dense foliage. They will therefore try to outgrow the top of the host tree. There will then be competition for light. The strangler fig's ample foliage will prevent the host tree from capturing enough light to survive. As a result, the host tree, "strangled", with insufficient light for photosynthesis and no possibility of growth due to the trellis formed by the strangler fig tree, will gradually die and rot in its hollow. All that will remain are the outer aerial roots and the gaping space between them. Some hollows are so large that it's possible to climb to the top of the strangler fig tree from the inside. These cavities and root systems form micro biotopes for numerous species. It is estimated that around 45.

Fig tree growth in brief

1. Seed dispersal by an external agent (birds, bats, etc.).
2. Epiphytic development of leaves and aerial roots.
3. The aerial roots touch the ground.
4. The roots grow around the support, forming a lattice.
5. The branches and leaves take over from the leaves of the support tree.
6. Little by little, the host tree rots.
7. All that remains is the strangler fig tree, with a void in its center left by the decomposed host tree.

A unique mode of reproduction

First of all, you should know that we only consumea single variety fig among the 750+ species of fig trees on the planet. We eat figs from the common fig tree. The fig is not a fruit, it's actually a structure called Siconum which contains the flowers of the fig tree. There are hundreds per fig. The fig tree can't rely on the wind to pollinate its flowers. This is where the wasp plays a vital role. This particularity leads to very specific and unique reproduction. In order to reproduce, fig trees have developed a mutualistic relationship with wasps (mostly from the Agaonidae) of millimetric size. This mutualistic relationship is so important that neither the fig tree nor the wasp can reproduce separately.

How does the fig tree reproduce?

As we've seen, figs are not fruits, but inverted inflorescences containing hundreds of flowers. Biologist Luciano Palmieri Rocha has established a 7-phase reproduction cycle. Phase A: The female flowers are not yet mature. They gradually ripen and become ready to be fertilized. The figs are then receptive to wasps for pollination, and figs emit large quantities of volatile compounds that are attractive to wasps. Phase B begins. Phase B: The female wasp must pass through a small hole, theostioleto access the fig flowers. This hole is so small that the female will lose her wings and antennae into the fig. The female wasp will then be unable to leave the fig. The wasp will die after laying its eggs. The wasp's eggs can be laid in many different flowers. By allowing the wasp to lay its eggs in these flowers, the wasp will pollinate other flowers. The flowers in which the eggs have been laid will harden and form structures known as "galls". Phase C: Flowers that have not received eggs and have been pollinated will turn into seeds. Phase D: This is the end of the larval incubation period in the flowers. Male flowers will also mature and expel pollen-containing anthers. There's a real synchronization between male flower ripening and the end of wasp development. Male wasps are small and wingless, and have powerful mandibles. They are the first to emerge from the receptor flowers, then move on to the flowers in which the female wasps are located. The male wasp then develops a telescopic penis that penetrates the envelope protecting the female wasp. Reproduction takes place at theinterior of this envelope. Once reproduction is complete, the male wasp digs a hole in the fig with his mandibles, emerges, falls to the ground and dies. The females then emerge from the receiving flowers. On their way to the hole dug by the male, the females will rub against the pollen-bearing flowers, pollinating other fig trees in the process. Phase E: The females fly off in search of other fig trees. This is the dispersion. Phase F: According to Mr. Rocha, this involvesan ecological phase. In fact, larvae of other species have been found in figs, without having any reproductive role for the fig tree. These include flies, beetles, ants, butterflies, moths and bugs. They use figs, either dead on the ground or directly on the tree, for various functions, but without any pollination role. As a result, figs are home to more wild species than any other fruit. To find out more about this study : http://www.sciencedirect.com/science/article/pii/S1146609X17300395

A tree that communicates

In order to reproduce without competing with other fig species in its immediate environment, it has developed a communication technique. When the fig tree is ready to reproduce, it emits volatile compounds (Phase A) which are received by other fig trees in the area. These will then delay their reproduction cycle. Once the first fig tree has completed its reproductive cycle, another will follow, also emitting volatile compounds to indicate to the other fig trees that it's its turn.  

The strangler fig, a legendary tree

L'history of mankind has always had a special place for fig trees. Buddha is said to have attained enlightenment under a fig tree. A branch was then cut off by Ashoka the Great, Indian emperor, who granted him the status of king and presented him with a solid gold vase. The strangler fig is so revered that Indonesia and Barbados have incorporated it into their coats of arms. Alexander the Great, the Greek Theophrastus, King Solomon of Israel, the Romans and the Vedic people all extolled the virtues of fig trees. The botanist Theophrastus was the first to mention the presence of small insects emerging from figs. King Nebuchadnezzar II planted ficus trees in the gardens of Babylon. Pharaohs had dried figs placed in their tombs to nourish their souls during the Great Journey. .