The life story of the banyan tree and the ficus bee

Wonderful world in ficus
The ficus plant is the only inflorescence of higher plants in the plant kingdom. All flowers are hidden in fruit-like receptacles, so it is called “fig.”

The ficus forms a fruit cavity in which the inflorescence axis expands into a urn shape. The small flowers grow on the inner wall of the fruit cavity. At the top of the inflorescence axis is a channel composed of a group of tile-shaped bracts. It is specially designed for pollinating insects-ficus bee to enter and exit freely. When the banyan tree reaches the flowering season, hundreds of thousands of flowers are hidden in each torus, and some even as many as tens of thousands of flowers. During the development of the torus, the ficus fruit also expands. When the fruit grows into a few days, the flowers in the cavity will open one after another, and release a burst of floral fragrance, attracting the ficus bee, the only pollinating insect of the banyan tree, to pollinate its flowers. After fertilization, the banyan fruit grows until it matures. The banyan tree relies on this peculiar way of flowering and fruiting to reproduce, live and multiply on the earth, pass from generation to generation, and form a large family of thousands of species.

There is a wonderful world hidden in the banyan fruit. The inner wall of the urn-shaped banyan fruit cavity is filled with dense and small flowers. It is obvious that the ovary of the drum is covered with long or short ribbon-shaped perianth pieces (when the sepals and When the petals look alike and are indistinguishable, we call the sepals and petals together perianth pieces). The base is supported by the pedicel, the ends are connected by a short style, and the top is the stigma. In the dark world, white and light yellow flowers are more common, but still retain some brightly colored flowers, some flowers ovary and style are red, but the pedicel and stigma are white; some flowers only perianth and The stigma is red and the other parts are white; some only the style and stigma are pink, and the rest are white; some of the whole fruit cavity is pink, red or red, and the degree of vividness is not inferior to the flowering plants that attract butterflies and butterflies.

People can only see the ficus and torus, and the blooming flowers are hidden in the fruit cavity

The encounter between the banyan fruit and the pollinating ficus bee occurred at the female flowering stage of the banyan tree. The female flower is opening. The color is not only pure and bright, but the original tightly covered shroud is loose, releasing a special fragrance to attract the pollinating ficus bee to visit. The pollinating Ficus bee searches for the fragrance of flowers and enters the fruit cavity of the female flowering stage along the loose top bracts. The mission of pollination and spawning is performed in the fruit cavity. This process lasts up to 2 days and is spawned or pollinated. For female flowers, the stigma color quickly darkens, the style shrinks, and the female flowers take off the glory of the past and instead conceive new life.

Rongguo-“The Comfortable Nest”
There is also a peculiar physiological phenomenon in the banyan community. Half of the banyan species have three kinds of flowers in the fruit, which are long stigma female flowers, male flowers and short stigma female flowers. These banyan trees are called androgynous banyan trees. Among them, the female flowers with long stigmas are pollinated by Ficus bees to form seeds; the female flowers with short stigmas are the “easy nest” for Ficus bees to reproduce; and the male flowers mature later, and the pollen will mature only when the seeds in the batch of ficus fruits mature. Therefore, when the long stigma female flowers open, it is necessary for Ficus bee to collect pollen from other plants with mature pollen for pollination and fertilization.

Another half of the banyan species differentiate into functional female ficus trees and functional male ficus trees, called dioecious ficus trees. They are divided into two different types of female and male plants. The flowers of the female banyan tree are all long stigma flowers. There are no mature male flowers in the fruit. The male flowers wilted and died at the early stage of development. The seed of the offspring; and the male ficus tree has female flowers and male flowers, and the flowers of the female flowers are all short stigma flowers, which are specially used for the spawning of ficus wasps. When the progeny of Ficus bee grows mature from the short style of male plant, and the adult pollen matures, the pollen is also mature. The female ficus bee collects the pollen and flew out. Most ficus bees carrying more pollen look for pollination of the blooming female ficus Most Ficus bees die in the fruit cavity of female plants after completing the pollination mission; while some Ficus bees that carry less pollen look for the short flowering male styles to spawn and reproduce. Both the banyan tree and the banyan bee each sacrificed part of their populations, each of which lost something, and also had gains, and mutual symbiosis. Most species of banyan tree only allow one species of ficus bee to pollinate it, and its floral scent also attracts only one species of pollinating ficus bee. Therefore, they form a one-to-one close mutually beneficial relationship, as long as one species is extinct, the other A species will also become extinct.

In the hermaphroditic banyan tree, the ficus bee prefers flowers with shorter styles, so that the ovipositor can more easily reach the ovary through the style head, and stimulate the ovary to expand into galls when laying eggs (worm galls are plant tissues that suffer from insects and other organisms) After feeding or spawning stimulation, the cells accelerate division and abnormal differentiation and grow into deformed tumors or protrusions, which are the “houses” where parasitic organisms live. The progeny of Ficus bee are in this bubble-shaped “easy nest” “Development and growth.” The bubble-like galls that infest Ficus wasps are round and large compared to the seeds. The long stigma female flowers in the inter-floral period are the most conspicuous ones. The ovary is constantly enriched and enlarged. The pedicels of different lengths and heights are distributed and arranged in different spatial positions, and the space competition is reduced to increase the space for reproduction. degree. In the late flowering period, developing male flowers can be seen in the ficus. They are often similar in color to female flowers, but they are shaped like animal kidneys, and vaguely can see kidney-type anthers. Most types of male flowers are much less than female flowers. .

After an inter-flowering period of 1 to 3 months, the male flowers in the ficus fruit mature and enter the male flowering stage, and the ficus wasps in the gall galls develop into the adult stage. After the emergence and mating, the ficus bees will leave the galls and enter the fruit cavity. Collect pollen on the mature male flower, or the pollen sac automatically ruptures, and a lot of pollen is released, which sticks to the wall of the pollinating ficus bee body. The male flowering period is shorter, basically completed in 1 day. The seeds are still developing silently. Later in the flowering period, the cephalocarp fruit flesh becomes soft and the seeds are mature. Some seeds are also coated with a layer of pectin, which is conducive to feeding animals to distribute their seeds.

The short stigma flowers all form galls, and there is a ficus bee embryo in each gall (Photo by Yang Darong)

The flowers in the fruit cavity of the banyan are blooming and the fragrance is overflowing. At the same time, the life cycle of new life and death is also staged. Because the banyan tree can only rely on the pollination of the ficus bee to complete sexual reproduction (the ficus bee is the only pollinating insect of the banyan tree), and the ficus bee must also rely on the female flower ovary in the ficus fruit to reproduce the offspring. Therefore, the ficus tree and the ficus bee You are inseparable from me, and I cannot do without your one-to-one co-evolutionary relationship. It is precisely the emergence of pollinating insects that promotes the evolution of plant diversity, so we need to protect the banyan tree and its pollinating insects, otherwise If one side is missing, the other side will also become extinct. That will be a misfortune unimaginable by mankind.