Understanding the Curious Rise of Bamboo - Science View

Leaves swaying gently in the wind. Long and striped, is this a tree or a grass? It's an even more curious plant, bamboo. Found mainly in Asia, there are said to be around 1,200 varieties in existence. It commonly reaches heights of over 20 meters. In that sense, it resembles a tree. Bamboo is neither a tree nor a grass. Bamboo is a plant that grows with almost unrivaled speed. At its base, something other than roots stretches through the ground. And its flowers bloom only once in a century? It's been said that it's been more than 120 years. Fascinating discoveries have been made on the plant, in unexpected fields. A structural engineer enamored with bamboo revealed the secrets of its complex form. I was really surprised that bamboo could make its own body so reasonably. I thought it was a really smart plant. The Curious Mysteries of Bamboo In this episode, researchers use their own perspectives to analyze its wonder. In April, spring comes to Japan. For 45 years, Shibata Shozo has studied bamboo, becoming one of its foremost experts in the country. Moso bamboo is the type of large bamboo found most commonly in Japan. It's thought to have been brought there from China around four centuries ago. Yellow-striped bamboo was given its name for the attractively contrasting yellow and green pattern that has made it a staple of Japanese gardens. Likewise, tortoiseshell bamboo is known as such for its rippled pattern. Black bamboo appears a much darker shade than most varieties. In all, there are around 240 types in Japan. What is it that makes bamboo so hard to classify? The black objects standing among bamboo thickets are the reason for this ambiguity. These are bamboo shoots. Every spring, they sprout up from the ground. What's especially remarkable is the pace of their growth. There's a reason for this startling pace. When the bamboo has just risen above ground, it grows a few centimeters a day. That speed continues to accelerate. After a few weeks, it's at its fastest. At this point, it grows an average of one meter a day. Even fast-growing trees such as the Japanese red pine require an entire year to grow a meter. In just two to three months, the bamboo attains its adult height of 20 meters. As to why bamboo experiences this growth spurt, Shibata explains that the answer is contained inside the shoot. When split vertically, it's hollow inside, divided by a shape like a board. When you look at it from the outside, this part is the stem. When the bamboo shoots become bamboo shoots, there is a layer that divides the cells in this part. Here, the number of cells increases and grows. The boards make up bamboo's characteristic segments. All of them contain an intercalary zone in which cell division is particularly active. Like an accordion, the segments expand at nearly the same time. A large amount of cell expansion occurring simultaneously forms the mechanism behind the swift growth. However, there's more to it than that. The cell functions require a large amount of energy to accomplish. It's provided from within the soil. Looking at the base of the bamboo, something is extending through the earth. It's the rhizome. This is its overall structure. Each stalk of bamboo is connected through the rhizome. The shoots sprout up from this network. Nutrients created through the bamboo's photosynthesis are provided to the shoots via the rhizome. The shoots are thereby supplied with ample nutrients by the bamboo around them. A wide area of bamboo is connected by a single rhizome. Its area is around 100 square meters, stretching as far as 25 kilometers in some cases. Rather than individual stalks, bamboo exists together as a massive colony of life. A certain fable is often told in Japan. It's known as the Tale of the Bamboo Cutter and is thought to date back to the 9th century. In it, a tiny baby girl known as Kaguyahime is born from within the bamboo and grows into a beautiful woman in three months. At the end of the tale, she reveals that she came from the moon and must return there. It seems very likely that this story was inspired by the otherworldly properties of bamboo. Over a thousand years ago, bamboo must have been seen as a mysterious and curious organism. It has been a familiar part of Japanese life for centuries. Many items from daily use or culture are crafted from the material. It's an essential element of the tea ceremony. For example, the tea whisk used to stir green tea. A single stick of bamboo is cut into thin spines and curved to fit the tea bowl. The bamboo's ideal balance of hardness and flexibility makes it ideal for bringing out the mellow flavor of the tea. It's a martial art that grew from samurai swordsmanship. In it, a sword called a shinai is made from durable bamboo. It was created so that warriors could hone their skills safely. Another use for the smoothness of bamboo is in traditional Japanese fishing poles. When they hook a fish, they bend flexibly but rarely break. This owes to the supple yet sturdy strength of bamboo. Light, durable, and smooth, these unique qualities of bamboo have long supported the growth of Japanese culture. One researcher became fascinated with the distinct properties of bamboo. Sato Motohiro is a professor of structural engineering. Having researched cylindrical structures such as tunnels and pipelines, he's an expert on the shape. Sato's curiosity was inspired as he considered bamboo to be a single structure. He became interested in what sort of functions were built into it. For example, this board here. This is called a diaphragm. From here to the top, there are several boards. Much like bamboo, the steel columns used to build condominiums are hollow inside. To reinforce them, panels are inserted at regular intervals along their height. Without these panels, they could easily break. If they were hollow, they'd be lighter, so they'd be more powerful. On the other hand, if they were hollow, they wouldn't function properly. So we need to reinforce them. That's why these columns are called diaphragms, and these columns are called bamboo. The reinforcement added to artificial structures is already found naturally in bamboo. This raises the question of what other mechanisms can be found in the plant. To find out, Sato began cutting open bamboo to measure every conceivable feature of it. In total, he measured more than 100 specimens. They yielded formerly unknown results. Lining sections of bamboo in order from the base up the width becomes progressively thinner. As for their segments, they start off close together, becoming farther apart around the middle. But surprisingly, they then get closer again near the tip. The cuts revealed even more information. At the base and tip, the walls of the bamboo show different thicknesses. These differences tell us more about the structure of bamboo. Sato proposed a formula that defines bamboo's legendary resilience. Inputting the measurements he made showed just how tough bamboo is. These are the results. The smaller the number, the more resistant the bamboo is to breakage. At the tip, the number is 5. In the middle, it's 3. And at the base, it's 1. This indicates that the closer bamboo gets to its base, the more resilient it is. And so, the tip of bamboo sways in the wind. The base, however, remains firm. The results of the formula demonstrate the superiority of bamboo in surviving the elements. His essay was selected from among U.S. physics journals for special notice by the editors. But resilience alone is not the answer to the question wasn't the extent of his discoveries. Bamboo has another mechanism concealed inside. It was found within the cross section. The speckled brown dots seen here are vascular bundles. Running all the way from the base to the tips, they transport water and nutrients throughout the bamboo. The vascular bundles are tougher than other cells, with a durability thought to be on par with steel. Sato took notice of their positioning. The bundles are sparse around the inside, becoming increasingly denser outward. According to his findings, this placement is deliberate. Rather than being arranged uniformly, the vascular bundles being concentrated outwards increases durability. In order to retain its resilience, the bundles are placed in this specific pattern. The wonders of bamboo are enough to astound even experienced structural engineers like Sato. The last property discovered within bamboo is an especially curious one. Researching the ecology of bamboo here is Kobayashi Keito. Kobayashi agrees to show us what he says is a particularly rare spectacle. The greenish-yellow flowers are proof that the bamboo is in bloom. However, what is it that makes them such a rare occurrence? Bamboo blooms so infrequently that many people never witness it during their lives. This video captured the moment, but there are no petals to be seen. Extending outwards from within the sepal are the stamens. After flowering, the bamboo quickly dries. In the 1890s, a newspaper reported that mass amounts of bamboo had dried out. Craftspeople specializing in bamboo objects were suddenly short on supplies. What causes bamboo to bloom so rarely and then dry up afterward? One theory states that by blooming all at once and releasing many seeds, it prevents mice and insects from consuming all of them. Another account suggests that it dries up to allow sunlight to reach a new generation of bamboo. Various such theories exist, but due to the plant's extremely long life cycle, no single researcher can observe its entirety. As it outlives humans, many mysteries remain nestled among the bamboo. How then to best get to the bottom of the bamboo? The answer lies in a mission passed down from Kobayashi's predecessors. This academic journal was published 96 years ago. It contains articles on bamboo, one with a notable plan. It's referred to as the 300-Year Project. The article states, Kobayashi has carried on this momentous project started by his predecessors. It contains various kinds of bamboo that have been observed for almost a century. In 2021, part of it began to change. In this area, moso bamboo had been growing. It was planted from seeds and raised. 66 years after sprouting, it bloomed and then dried up. In other words, the entire life cycle of bamboo was observed here. This photograph was taken by Kobayashi to commemorate the bloom. Two researchers stand proudly beneath the flowering bamboo. On the right is Shibata Shozo, the bamboo researcher who appeared earlier. On the left is Watanabe Masatoshi, who watched over the bamboo since it was first planted. And so it transpired that three generations of researchers collaborated on the 300-Year Project. I will never live to see the next flowering bamboo. The next researcher, Kobayashi, will follow in my footsteps. Without him, I would not be able to carry on my research. I believe that I have become one of the gears in the process. I am happy about that. The seeds harvested from the bamboo's blooms have already been planted nearby. These stalks sprouted just two years ago. The bamboo that will eventually reach heights of 20 meters begins in such a tiny state. It has already extended its rhizome, sprouting small bamboo shoots. The plant has only just begun its life cycle, with many changes to come. It's been less than 100 years, so it's still only a third of the way through. We still have 200 years to go. It's a long time. I wonder what the world will be like. I would like to see it, but I don't think I can. 200 years remain of the 300-Year Project. It seems safe in the hands of new generations of researchers. Possibly the most curious trait of bamboo is its ability to fascinate people in all walks of life.