Liu Bing: How many unique plants are born in the magical Madagascar?

“On this island, we can see seven species of baobab trees at the same time.”

Liu Bing

Assistant Researcher, Institute of Botany, Chinese Academy of Sciences

Good afternoon everyone, my name is Liu Bing, and I’m from the Institute of Botany, Chinese Academy of Sciences.

Because of my work, I often go to Africa, including the African continent and Madagascar Island, to conduct field plant surveys. Especially on the island of Madagascar, there are many trees with strange shapes. Because these trees are similar to my style, the trunks are swollen, just like having a big belly. So I was deeply attracted by them at that time. Today I want to introduce these trees with big bellies on the wonderful island.

Magical Madagascar

When you mention Madagascar, the first thing that comes to mind is the cartoons called "Madagascar". One of them is called "Penguins of Madagascar", but many of the animals in it, such as lions, hippos, giraffes, zebras, etc., are not animals from Madagascar, because they are all from the African continent.

Of course, the plot of this movie is about animals from zoos and circuses that drifted to Madagascar, but the real native animals on the island are actually other groups.

Madagascar is located on the west coast of the Indian Ocean, southeast of the African continent. It is the fourth largest island in the world, second only to Greenland, New Guinea, and Kalimantan. Interestingly, although Madagascar is an African country, most of its residents look more like yellow people.

The left picture shows their current president, and the right picture shows the photos we took there. Although the skin color of the locals is a little dark, it doesn't look that dark, and it is different from the black people on the African continent.

Research has found that over the past 1,000 years, some people from Southeast Asian islands, such as Indonesia, have rowed across the Indian Ocean island chain and arrived at Madagascar. Later, some black people from the African continent also came to Madagascar. The two groups of people lived together and intermarried. So now the appearance of people on the Madagascar Island is still close to that of the yellow race.

You may have seen the various lemurs, strange chameleons and other strange animals on the Falkland Islands in the TV series "Animal World". In fact, in addition to these, the plants on the island are also very strange. Today I will mainly introduce you to the content about plants.

According to the different climate types, we can divide the island into four parts: the easternmost strip is the most humid area, which is called the rainforest area; the middle part is a slightly humid area, which is called the plateau area; the west is divided into two parts, the southwestern part is the driest place, namely the southwestern arid area, and the northern part is called the western semi-arid area. The plants we introduce today are mainly distributed in the semi-arid and arid areas in the west.

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Those strange-shaped baobab trees

Baobab tree Adansonia digitata Malvaceae

In the savannah of Africa, there are two seasons a year, the dry season and the rainy season. This is a baobab tree in the dry season of Africa, and all the leaves on the tree have fallen off.

Baobab tree Adansonia digitata Malvaceae

During the rainy season, there is a lot of rain, so the grassland is very green and the trees are very bright. This is a baobab tree during the rainy season (left), it is very green and full of leaves. During this season, the baobab tree will also bloom (right), the flowers are white and very large.

Baobab tree Adansonia digitata Malvaceae

When the fruit is ripe, it is the dry season. All the leaves have fallen off and the tree is full of fruits. If you break the fruit open, there will be some seeds and some fibrous pulp inside. The pulp is sour and sweet and tastes good. The locals add water and sugar to make a kind of baobab juice, which tastes quite good.

Breadfruit tree Artocarpus altilis Moraceae

I would also like to clarify that the baobab tree is different from the breadfruit tree. The breadfruit tree is actually another plant, and it is a distant relative of the baobab tree. The baobab tree is a plant of the Malvaceae family, while the breadfruit tree is a plant of the Moraceae family. It is actually a member of the jackfruit family. When the fruit of the breadfruit tree is ripe, it is picked and steamed in a pot, and it becomes a food that tastes like bread and can fill your stomach. However, it is very difficult to get full by eating the flesh of the baobab tree.

Baobab trees are distributed over a large area in the African continent, but there is only one type we just introduced. However, on the wonderful island of Madagascar, there are six types of baobab trees, which is much more than on the African continent. At the same time, Madagascar also introduced the native species of baobab trees from the African continent. So on this island, we can see seven types of baobab trees at the same time.

Avenue of the Baobabs

This is a very famous landscape in the west coast of Madagascar, called the Avenue of the Baobabs. You may have seen it online, and it is even printed on local currency.

Adansonia grandidieri

This is another type of baobab tree, called the giant baobab tree, which is the largest in the entire baobab family. This giant baobab tree is at the end of the dry season, and tender green leaves are slowly growing on the tree to welcome the arrival of the rainy season.

Adansonia grandidieri (Malvaceae)

The left picture shows the flower of the giant baobab tree, and the right picture shows its fruit. Its fruit is a little smaller than the one mentioned earlier, but it is also edible. When traveling in the local area, there will be residents setting up stalls to sell these fruits. The taste is similar to the previous one. If you have the opportunity to travel there, you can also try it.

Red-skinned Baobab Adansonia rubrostipa Malvaceae

Other types of baobabs have more peculiar shapes. For example, the red-skinned baobab tree in the picture above has slightly reddish bark and is shaped like a wine bottle standing on the ground. The red-skinned baobab tree in the picture on the right looks like two wine bottles.

Red-skinned Baobab Adansonia rubrostipa Malvaceae

This is its flower (left), which is composed of yellow stamens and red calyx, and is very colorful. Its fruit is also a reddish-brown fruit (right).

This baobab tree grows in the driest areas of the southwest. In those areas, all plants have one characteristic, which is to endure the season without water. The dry season here can last up to nine months, and only in the remaining three months can we wait for a little rain. So the trunk expands like this to store water to survive the unbearable dry season.

Red-skinned Baobab Adansonia rubrostipa Malvaceae

The red-skinned baobab tree on the left looks like a thermos bottle, and the tree on the right is even fatter. If you want to surround it, you may need ten people holding hands to do it. It is said that there is a fatter tree than this one, which grows into a big disk, but because the transportation to that place is not very convenient, we did not go there.

Red-skinned Baobab Adansonia rubrostipa Malvaceae

These trees grow in various ways; some grow at an angle, some fork from the bottom, and some grow two tumors on the top.

The previous introduction was about the state of baobab trees in the dry season, so what do they look like in the rainy season?

rainy season

Because the productivity level in the area is relatively low, the traffic conditions in many places are quite bad. When the rainy season comes, although there is rain, the traffic will be very bad. For example, when we climb mountains or cross rivers there, we have to wade through the water, and the local residents are the same as us. Sometimes the road is washed away by the flood, and the car is stuck in the mud, and we have to find a way to find a rope to pull it out.

Red Baobab Tree Adansonia madagascariensis Malvaceae

During the rainy season, the baobab tree will be covered with green leaves. This is the red baobab tree, and its bark is bumpy, indicating that it has experienced hundreds or even thousands of years of vicissitudes.

Red Baobab Tree Adansonia madagascariensis Malvaceae

This tree will bloom with relatively large red flowers throughout the tree during the rainy season, so large that they can even cover the entire trunk.

Red Baobab Tree Adansonia madagascariensis Malvaceae

The picture above is a close-up of these flowers. They are bright red and very beautiful.

Adansonia perrieri (Malvaceae)

This is the big-fruited baobab tree, which grows in a wetter environment than other baobab trees, and has a shorter dry season. Because the environment is humid enough, there is no need to store so much water, so its trunk does not look that swollen from a distance. Only when we look at the bottom of its trunk can we find that it has a little bulge.

Baobab fruit

The big-fruited baobab tree is the species with the largest fruit in this family, and its fruit can reach up to 40 centimeters in size.

Elephant Birds Aepyornithidae

Let's look at another peculiar creature: On the island of Madagascar, there was once a bird that was closely related to the ostrich, called the elephant bird. It could grow up to three meters tall, taller than the ostrich. However, after humans migrated to the island, many forests and suitable ecological environments were destroyed, and the elephant bird became extinct hundreds of years ago. But now we can find many eggshell fragments that it left behind. For example, this egg model (right in the picture) is made of those eggshell fragments, and it looks similar to the fruit of the baobab tree.

Baobab trees are plants that cannot move by themselves, so they rely on animals to eat their fruits to spread their offspring. According to research, elephant birds are very important for the spread of baobab tree seeds. When the fruits of baobab trees are ripe, elephant birds will eat them. After eating, the seeds in the fruits will be excreted through the digestive tract of elephant birds and then spread to farther places. Since the seeds are excreted with the feces of elephant birds, when the seeds germinate, this pile of feces happens to be its natural fertilizer. This is a win-win situation.

Another characteristic of the baobab tree is that its seeds must be processed and excreted by the digestive tract of the elephant bird before they can germinate smoothly. If they do not go through this process, it is difficult for the seeds to germinate under normal conditions. Therefore, after the elephant bird became extinct, if humans do not intervene, the baobab tree may also face the fate of extinction in the future, because there will be no animals to help it process its seeds. But the local people will help it, that is, to plant baobab trees. This is actually similar to passing through the digestive tract of the elephant bird. After we scald the seeds with hot water, it is easier for them to germinate. This is the relationship of mutual co-evolution between local animals and plants.

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The exquisite structure is the wisdom of survival of the royal poinciana tree.

There is a large area of ​​karst landforms in the western part of Madagascar, which is a continuous limestone mountain. my country also has large areas of karst landforms in Yunnan, Guangxi and Guizhou. In the local karst landforms, due to long-term drought and lack of rain, many trees grow into big belly shapes, and the poinciana tree is one of them.

Karst landform

Because the flowers of the royal poinciana tree are very beautiful, many places in southern my country now cultivate this tree for ornamental purposes. The royal poinciana tree is a leguminous plant, and its fruit is a long, flat bean pod.

Delonix regia Leguminosae

The origin of the Poinciana tree is also in Madagascar, but it is located on the island near the sea where there is plenty of rain, so it does not need to grow into a big belly. Water is enough. However, many of its similar Poinciana trees grow in very dry limestone mountains, so they need to grow into a big belly shape.

Delonix velutina

For example, the short-haired Poinciana grows on a very barren limestone mountain. If it doesn't have flowers, its entire bark is the same color as the stone. The entire trunk of the short-haired Poinciana looks like it has emerged directly from the stone, which shows that it has lived for a long time and is very resistant to barrenness.

Delonix velutina

The short-haired Delonix regia blooms during the dry season and its flowers are light yellow.

Delonix decaryi Fabaceae

This is the Apricot-yellow Poinciana. Its big belly has a special feature: it is thick in the middle and thin at both ends, and the whole shape is like a spindle. If it is so long, will it be blown down by a gust of wind? The answer is no. A trick of the Apricot-yellow Poinciana is that its roots extend in all directions on the ground, forming a shape of a bird's claw. The two trees in the left picture are like the two claws of a bird firmly grasping the ground, very stable. The picture on the right is the fruit of the Apricot-yellow Poinciana, which is also a long bean pod.

Moringa drouhardii Moringa drouhardii

There are other species living in the karst area with the royal poinciana, such as the elephant's leg tree of the Moringa family. You can also see why it is called the elephant's leg, because its trunk is like an elephant's leg.

Fruit of the elephant foot tree

The fruit it produces is very long, like a bean pod.

Moringa drouhardii Moringa drouhardii

The elephant's foot tree grows by the sea, but when we visited, local residents told us that due to the climate, it has not rained for two and a half years in this place, and it has been in the dry season. How can the local plants survive without rain for such a long time? Fortunately, they are close to the sea and can survive on the moisture blown by the breeze from the sea every morning. This living environment is very harsh.

How does the elephant's foot tree spread its seeds? When its fruit is ripe, it will split open, and the seeds inside will have two small wings. These wings can carry the seeds to float in the wind and drift to some distant places.

Gyrocarpus americanus

This plant is called the spiral wing fruit, and it grows together with the royal poinciana, elephant's foot tree, etc. The trunk of the spiral wing fruit is also relatively swollen, similar to the elephant's foot tree, and the structure it uses to spread its offspring is also wings, and the two wings on this fruit are staggered in two directions. When the fruit matures and falls, it can rotate at high speed like a helicopter propeller while falling.

Why do we do this? This is because without the wings, the fruit will fall directly to the bottom of the mother tree. However, due to the blockage of the big tree, the fruit germinating at the bottom of the mother tree is very detrimental to the subsequent growth. With wings, the falling speed of the fruit will be much slower. During this process, if there is a crosswind, it will be blown to other locations.

It is with this ingenious structure that the spiral fruit is able to spread its offspring to further places. This is the skill of spreading fruits by wind, and it is also the wisdom of plants.

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Thorns and milk: the club-hammer tree's weapons of self-defense

The next type of plant to be introduced is the hammer tree, which gets its name from the fact that its entire trunk looks like a hammer.

Pachypodium rutenbergianum Apocynaceae

The picture above shows one of the hammer trees. The trunk is thick in the middle and thin at both ends, and looks like a hammer.

Pachypodium rutenbergianum Apocynaceae

This is the flower of the shamrock tree. It grows leaves in the rainy season and bears flowers and fruits in the dry season. If you look closely, you will find that there are many thorns under the flower and fruit branches of the shamrock tree. These thorns are the weapons that the shamrock tree uses to protect itself and prevent animals from eating it or damaging its leaves.

Mace Pachypodium geayi Apocynaceae

There is also a kind of hammer tree called mace, which has been introduced in some greenhouses in our country. For example, the picture above is a mace planted in a domestic greenhouse. Why is it called mace? This is because its trunk is full of dense thorns, just like a weapon like a mace.

So what does a mace look like in the wild of Madagascar?

Mace Pachypodium geayi Apocynaceae

It looks like the picture above. It is very tall and stands out among the bushes.

Mace Pachypodium geayi Apocynaceae

When the mace was small, it had thorns on the trunk, but when it grew up, the thorns fell off. In the picture on the right, you can see small dots, which are the traces of the thorns falling off.

In addition to thorns, this plant has another weapon to protect itself, which is the milk in its body. Even those herbivores that are not afraid of thorns will be poisoned by the milk if they eat its leaves. Although the tree has no thorns, its milk can still keep many herbivores away.

Pachypodium densiflorum Apocynaceae

In addition to this tall sedge tree, there is another shorter type that is less than one meter tall. Compared to a person, this sedge tree looks like it is growing underground.

Pachypodium densiflorum Apocynaceae

The base of this tree is also swollen, and there are many dense thorns where the young leaves grow, which is also used to protect its leaves from being eaten. It blooms in the dry season, and the yellow flower on the right is its flower.

Pachypodium rosulatum subsp. gracilius Apocynaceae

This is also a short hammer tree that grows on limestone mountains. The base of the plant is a large fat structure filled with water and nutrients.

Pachypodium rosulatum subsp.gracilius Apocynaceae

Look, doesn’t it look like a Maitreya Buddha lying here, with some flowering branches growing on it?

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Plant with a trunk like a bucket - Grape jar

The type of plant introduced below is said to be a tree, but it is actually not a tree. It is a vine called a vine.

Grape Vitis vinifera Vitaceae

Everyone knows that grapes are a vine plant. When planting grapes, you need to build a trellis for it, let it climb on the trellis, and then produce bunches of grapes.

Grape urn Cyphostemma spp. Grape family

In Madagascar, there is a type of grape in the grape family called grape jar, its leaves and fruits are similar to grapes.

Grape urn Cyphostemma spp. Grape family

There are some tendrils growing on the branches of this small green fruit. Tendrils are the branches that the plant uses to climb other plants when it is climbing: one tendril wraps around a certain place to hold itself, and then another tendril wraps around another branch, thus slowly climbing up.

Grape urn Cyphostemma spp. Grape family

Why is this plant called a grape jar? This is because it also has a big belly. The picture above shows the swollen stem at the base. The left side is the rainy season, and the right side is the dry season. In the rainy season, the leaves grow out and are particularly green; in the dry season, it looks like a dead tree.

Grape urn Cyphostemma spp. Grape family

There is also this kind of grape jar that grows stronger, its vine can grow to a very high position. At the very bottom of the stem there is a particularly swollen trunk, just like a water jar, so it is called a grape jar. It is said that this is the largest grape jar in the area, and it may be hundreds or even thousands of years old.

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The water-spraying traveler's banana

Ravenala madagascariensis Strelitziaceae

Finally, let’s take a look at a plant that doesn’t have a big belly: it is called the traveler’s banana, a plant native to the island of Madagascar and very common there.

For example, if the original forest on a hillside is cut down by people, or burned by lightning, some plants will spread here and occupy this area immediately. Traveler's palm is a plant that likes to occupy the destroyed forest land. In just a few years, it can grow densely on the hillside it occupies.

Ravenala madagascariensis Strelitziaceae

All the leaves of the traveler's palm grow at the top of the plant, arranged one by one in a fan shape. Because the traveler's palm is a world-renowned plant with Madagascar characteristics, the locals have printed the traveler's palm pattern on their coins and even on the national emblem. Their airport is also called the Traveler's Palm International Airport.

Why is this plant called traveler's palm? This is because in the desert, if a traveler is thirsty, he can cut the petiole or stem of the traveler's palm, and water will flow out.

Ravenala madagascariensis Strelitziaceae

Is this story true? I think it is half true and half false. Please take a look at its leaves. The base of its petiole grows very densely. If we poke it with a knife, water will indeed flow out, but not much.

In the picture, a little water has flowed out. We did a field test at that time. If we find ten traveler's palms, only four or five of them can produce some water, and the amount of water is just a drop in the bucket, not enough to drink.

In addition, the traveler's palm cannot grow in deserts and deserts because those places are too dry, and it does not have a swollen belly to store water. It needs to grow in relatively humid places, such as semi-arid or semi-humid areas. So it is impossible for travelers to find traveler's palm in the desert, because it does not grow at all, and even if it does, the amount of water may be very small.

Our local experiments have shown that only part of this legend is credible.

That’s all for today’s sharing. I hope that students who are interested in nature will go out into the wild and into the mountains to get closer to nature and explore the mysteries of the animal and plant world. Thank you!

Source: Gezhi Lundao Forum