Chocolate was cocoa beans before it became chocolate. Cacao beans are the seeds of the cacao tree, and the cacao fruit is the fruit of the cacao tree. A cacao fruit contains 30-50 cocoa beans (seeds), which are processed into chocolate by humans. Before chocolate, humans used the cacao tree not to make chocolate, but to eat the flesh of the cacao fruit.
Cocoa fruit
Cacao fruit is a nut that can be eaten. (Nuts are a kind of closed fruit, the skin is hard, and the closed fruit containing 1 or more seeds is called a nut)
For friends who have seen cocoa trees, you will find that cocoa trees are different from most fruit trees such as apple trees and pear trees, it does not grow on branches, but directly on the thick trunk.
Grafted cocoa tree
Why does the cacao tree grow its fruit on the trunk?
< h1 class= "pgc-h-arrow-right" > strange old stem fruit</h1>
As for the cocoa fruit on the low trunk, it has been explained that this is due to the weight of the cocoa fruit, the branches can not hang at all, so it evolved to the trunk. In order to prove this point, some people have given the example of paramita, saying that the fruit of paramita also grows on the trunk, also because the weight of the fruit is too large, hanging on the branch is easy to break the branch and fall down.
Baltic honey tree
A cocoa nut weighs about 2 pounds, which is a bit heavy in terms of weight. This use of the "weight of the fruit" to explain why the fruit grows on the trunk of the tree seems to make some sense.
In fact, however, we do not believe that this statement is correct.
First, let me give you a counterexample. If the fruit is heavier and should be hung on the trunk, then how to explain the tree grapes?
Tree grapes
The fruit of the tree grape is not heavy, but it also grows on the trunk? Therefore, we believe that the weight of the fruit does not affect where the fruit grows.
In botany, we usually refer to the phenomenon of this fruit growing on the trunk of the tree as "old stem fruit". Old stem fruit usually occurs in tropical fruit trees, for example, we are talking about cacao trees native to the tropics of South America, tree grapes are also fruit trees in the tropics of South America, and polo honey is also a fruit tree in the tropics. In the northern temperate zone, there are almost no fruit trees with old stems, and most fruit trees such as apples, pears, peaches, and apricots grow on the branches of the fruit tree canopy.
cacao
Similarly, some people explain the phenomenon of old stem fruit from the perspective of nutrient delivery, believing that the old stem of fruit trees is thicker and has more sieves, which can better provide nutrition for denser fruits.
This explanation is not like explaining the reason, but more like explaining the advantages of the old stem results. Assuming that the old stem fruit really has such a big advantage, why didn't higher plants such as apples and pears evolve the old stem fruit?
Inside the fruit of the cacao fruit
This statement does not make sense.
The old stem fruit should not be a phenomenon of higher evolution, but rather a primitive phenomenon of plant fruit. Old stem results are not necessarily of any benefit, and it is likely that they were forced to carry out "old stem results".
There is a saying that "existence is reasonable!" "But in the evolution of plants, existence is not necessarily reasonable. Evolution cannot only take advantage of the loss, there is a give-up, the phenomenon of "old stem fruit" is more like a side effect of plant evolution. Why? Let's start with another phenomenon.
<h1 class="pgc-h-arrow-right" > old stems and flowers</h1>
If we ask what is the fruit developed from? Many people will mechanically reply that the fruit of a plant is developed from the ovary. This statement is naturally correct. But if we are more macroscopic, such as the whole apple, which organ of the plant develops from?
In fact, it is the flower of the apple, and it is impossible for the apple to produce fruit without flowering. Flowers are the reproductive organs of plants, seeds are the offspring of plants, and fruits are the "cradles" of plant offspring.
cacao
Plants have one of the biggest differences from animals, animals can run around, but most plants can't. Animals can choose different locations in mating, while plants cannot. The mating of plants is passive, in order to better reproduce, plants can only attract insects by flowering, spread their own pollen, and attract other people's pollen.
The basic logic in the evolution of plants is that "all evolutionary actions are for the purpose of reproducing.". The basic route for reproduction is to find a "pollinator". Pollinators are usually smaller insects, and whoever attracts more insects has more opportunities to reproduce.
Attracting insects depends on the reproductive organs of plants, that is, flowers.
The old stems of the tree grapes are full of flowers
To explain the phenomenon of the old stem fruit, it is also necessary to explain it from the perspective of the flower. Before the old stems bear fruit, the old stems will flower, and the cocoa tree and the tree grapes will blossom in this way. Why bloom on the trunk of a tree? From the point of view of "reproduction is the purpose of evolution", the purpose of this is definitely to make their flowers more conspicuous and attract more insects.
The trunk is shorter than the canopy, the trunk takes up less space for flowering, and the flowering on the trunk is less competitive at the same height than the flowering on the canopy.
Starting from these three "benefits" and combining the tropical rainforest environment, we can have two reasonings: one is that the pollinators in the tropical rainforest do not fly high and can only fly to the trunk; the other is that the tropical rainforest plants grow too high and dense, and there is not much "pollination" space to fight for in the "canopy" space.
The old stems of the cacao tree are flowering
Since the tropics have the most species of bees, the first reasoning is not true, and it is not that pollinators do not fly high.
The second reasoning holds. The trees in the tropical rainforest are mostly trees, growing very tall and dense, and the competition for plants is very fierce at the height of the "canopy". If the flowers bloom on the extended branches of the canopy, they are likely to be obscured by other trees, which is not conducive to insect detection and leads to a decrease in the chance of pollination. Growing on tree trunks, the space is relatively open and can better attract insects to pollinate.
This also has old stems and flowers.
<h1 class="pgc-h-arrow-right" > which is higher, the fruit on the branches of the canopy and the old stems? </h1>
If the logic of old stems and flowers is true, then the old stem results can be explained. The fruit is developed from the tissue in the flower, and the cacao tree blooms on the trunk to better attract insects. This is positive action. But "it is a three-point poison of medicine", it blooms on the trunk of the tree, and the "fruit" as the cradle of the offspring can only hang on the trunk.
Therefore, we say that the old stem flower is an evolutionary choice and has a role; while the old stem fruit is useless, the plant blossoms on the stem, where the fruit is already predestined.
Plants with old stems have to bloom as many flowers as possible on the empty trunk in order to reproduce, which is actually a last resort in order to reproduce.
Cocoa trees, tree grapes, polo honey and other fruit trees with old stems should all belong to the fruit trees that "take a step back from the sea and the sky", but they can't hide, knowing that there are tigers in the mountains, then they don't go up the mountain.
This may be an evolutionary strategy for these plants. The fruit of the old tree is not a high-level evolution, and the old stem is the forced product of the flowering of the old tree.
This way of resulting is not only not advanced, but also useless to the fruit itself. While the fruiting branches of the canopy blossom and bear fruit, the amount of fruit flowering and fruiting is greater, the space for expansion is more, and more fruits and seeds can be produced.
Cacao fruit has a variety of large fruits
From this point of view alone, it seems that fruit trees such as peaches and apples win, and the fruit trees that bear fruit branches in the canopy are more advanced, while the plants that bear fruit on old stems are defective. In fact, there is really a defect of "few results".
For fruit trees with old stems, two more evolutionary paths have been taken to compensate for this deficiency. One road is "dense fruit", with densely packed fruit covering the trunks. The most typical are tree grapes, wood milk fruits and so on. The other path is "large fruit variety", a large fruit contains a lot of seeds, such as the cocoa tree, a fruit with 30-50 seeds. Paramita is also a "variety of big fruits".
And in fruit trees that bear fruit on the canopy, there are not so many seeds in a single fruit.