The Chinese Banyan Tree on the Slope Behind the Centre
- Dec 8, 2020
- 5 min read
Updated: Feb 14, 2022
Part 1
The Chinese Banyan Tree on the Slope Behind the Centre
There is a Chinese Banyan tree on the slope behind the centre. The slope was trimmed at the beginning of the year, revealing the roots of the tree that were originally covered by weeds, its rhizomes firmly gripping a low stone wall.
Stonewall trees constitute the unique urban landscape of Hong Kong, demonstrating the tenacious vitality of nature. The emergence of this banyan tree should be the same as that of many other stonewall trees - when an animal ate the fruit of a Chinese Banyan, and went near the stone wall, the indigestible seeds fell into the cracks of the stone wall along with their faeces and sprouted.
The Chinese Banyan is a common ficus plant in Hong Kong. Among the 462 trees in Hong Kong's Register of Old and Valuable Trees, 223 are Chinese Banyan! Its vitality is astounding. As long as there is a little space, the long and dense air roots will continue to absorb moisture and nutrients in the air, so that the ficus can continue to expand its canopy and extend the aerial roots until they touch the ground. Once the aerial roots reach the ground, they will lignify and become a new pillar for the tree. The new pillar allows new aerial roots to extend even further from the tree.
The fruit of the banyan tree, the fig we usually talk about, is not actually flowerless (the Chinese name of the fruit, translated literally, means “flowerless fruit”), nor is it a real fruit. The "fruit" (fig) we see is actually a receptacle. When you tear apart the “fruit”, you will see the flowers of the Chinese Banyan. Then how is the Chinese Banyan pollinated? It depends on its "matchmaker", the fig wasp. The structure of the banyan fruit of each banyan tree is different, so most of them have unique and dedicated fig wasps, which can penetrate into the banyan fruit to pollinate the florets, and at the same time lay eggs in some of the flowers, sharing a symbiotic relationship.
In 2018, the super tropical cyclone “Mangkhut” struck Hong Kong and broke some of the branches of the banyan tree at the Centre. The Centre then cooperated with Chi Kee Sawmill & Timber to organize a workshop to make wood chairs and bookshelves for participants to take home. Two years have passed, and since then the banyan tree has grown new branches. When you come to the center next time, besides admiring the plants in the garden, you should take a look at the banyan tree behind!
Part 2
Life of a Fig Wasp
Fruit of the Chinese Banyan
©️Agriculture, Fisheries and Conservation Department Specimen Room
The fruit of the banyan tree, the fig we usually talk about, is actually a receptacle. The grains you see when you tear it apart are the flowers. They are divided into male flowers, female flowers and gall flowers (the unique neutral flowers of the banyan tree, they do not produce pollen, and are only for the fig wasps to lay eggs and hatch in). Although some banyan trees are monoecious, most of them are dioecious to avoid self-reproduction. The flowering time of the dioecious trees are different, so that self pollination within the same fig does not occur. As such, the fig wasp plays a critical role as the matchmaker of the Chinese Banyan tree.
The mother fig wasp will burrow its way into the fig. It may lose its antennae and wings in the process. Then, it will lay eggs within a type of flower called gall flower within the fig. After its hard work, the mother fig wasp is unable to leave the fig as it has lost its ability to fly.
The male fig wasps will hatch first. As they have no eyesight nor wings, they can only mate with other female fig wasps within the same fig. After mating, the male fig wasp will bite a hole in the fruit wall, so that the female fig wasps, who will become a mother after mating, can fly out to find another fig to lay eggs in. Because the female fig wasps carry pollen from the male flower in the fig that it was born in, the fig wasps help pollinate the Chinese Banyan. This is how the fig wasps and banyan tree share a symbiotic relationship.
Can't imagine how it happens? Check out this YouTube animation (in English) that introduces the life of a fig wasp and the pollination of a banyan tree:
The pollinating female fig wasp has a slender head that helps it burrow into the fig
There are many types of fig wasps, and different from the ones introduced this time, some species have very long ovipositors. They can lay eggs without having to penetrate through the skin of the figs, so they do not assist in pollination.
Some people say that while eating figs, you may be accidentally ingesting the carcasses of fig wasps as well. On the contrary, dead fig wasps will be quickly decomposed and absorbed by the enzymes of the figs. Generally, the crunchy parts of the fig are its seeds, and the chance of eating the carcass of a fig wasp is tiny.
Part 3
Common Red Stem
Figs of the Common Red Stem
When the female flowers in the "banyan fruit" are successfully pollinated, they will develop into fruit. The fruits hidden in the receptacle of the "banyan fruit" are so small that they are invisible to the human eye. Regardless of whether the pollination is successful or not, for many wild animals, the ripe fig is a tasty snack. Local birds love to eat the fig, so the seeds of the banyan that have not been digested often have the opportunity to land on the stone walls of the city by bird faeces to develop a new life.
Compared to the banyan tree, the Common Red Stem in the center garden is more popular! Not only are human visitors interested in the figs that grow directly from the tree, but it's fruits attract many neighbors from Lung Fu Shan day and night. The Weaver Ant also builds nests on the Common Red Stem. Thus, a single tree can give birth to countless lives.
The Common Red Stem is commonly seen in both urban and suburban areas of Hong Kong, but it is different from the Chinese Banyan Tree on the back slope of the center that was "born" through natural reproduction. The Common Red Stem in the centre’s garden was actually planted by the former resident Stephanie 30 years ago. It is true that when our ancestors plant trees, the later generation gets to enjoy the shade~
This masked palm civet, which is usually nocturnal, cannot resist the temptation of the sweet-smelling figs. It is rare for it to feed when the sun is still up.
Short-nosed fruit bats live up to their name by eating fruit to stay alive, and figs are their favorite.
The figs that fall on the ground will be "processed" by the East Asian porcupine (porcupine) at night.
Certain butterflies, such as the Baron butterfly in the picture, will feed upon the juice of rotten figs.
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