Plants need to spread their seeds as far as possible so that offspring have enough room to live and there isn’t too much competition among each other for resources. Some plants disperse their seeds over great distances with violent movements, like explosions. This mechanism of using kinetic energy to disperse seeds is called “catapult dispersal” and is used by several plants including the legumes, euphorbiaceae, acanthaceae and cucurbitaceae. These plants basically shoot the seeds out of the pods by bursting open the pods.
The scariest “exploding” plant is the rattle box. The ring box’s trunk has the iconic cone-shaped spines of Euphorbiaceae, but its most dangerous part is the pumpkin-like fruit. Although the fruit of the rattle box looks like a pumpkin, ingestion of the flesh by humans or wild animals can immediately cause vomiting, diarrhea and muscle cramps. The gum in the ring box fruit is highly toxic. People will develop rashes after contact with the skin, and may cause blindness after contact with the eyes. What is even more frightening is that these “pumpkins” will “explode” at any time when they are ripe.
There is a layer of septum between the petals and seeds of ring box fruit. The septum is initially attached to the fruit valve, firmly maintaining the integrity of the fruit valve. As the fruit gradually dries, the fruit petals are gradually separated from the septum, and the fruit petals gradually lose their restraint. Dehydration deforms the petals, accumulating elastic deformation. As soon as the connective tissue at the edge of the fruit petal begins to crack, the bursting of the fruit petal can no longer be stopped.
Sphagnum moss is a very primitive plant that grows close to the ground and only grows to a height of 1 cm. Its sporangia are like miniature cannons, ejecting a miniature mushroom cloud composed of tens of thousands of spores. It can accelerate the speed of spores to more than 100 kilometers per hour in less than one thousandth of a second. In 1897, a Russian biologist wrote: “Several times I stooped to observe the sphagnum moss at close range, and felt the cap hit my face.”
Despite the rapidity of the eruption, the spores were too small. After overcoming air resistance, they can only rise to a height of more than 10 centimeters from the ground. This height does not sound very high, but it is enough for the spores to take a “ride” on the near-earth airflow. If they encounter the right updraft, they will be carried thousands of meters away or even farther.
Sphagnum spore clouds are ejected in eddies. The spore cloud erupted from the sporangia is like a tornado connected end to end. This eruption form can not only greatly reduce the resistance of the air to the spore cloud, but also maintain the overall shape of the spore cloud. This way, only a few spores are left behind in the transmission process, and most spores can be spread far.
The “explosion” process of the cucurbit plants spraying melons is very spectacular. The fruit of the melon is very small, but after ripening, high pressure will accumulate inside the fruit, causing the fruit to detach from the fruit stalk, and a small hole will be opened in the fruit, and the juice and seeds in it will suddenly erupt violently from the small hole, and the whole The process is like severe diarrhea. Coincidentally, cucurbitacins are contained in the seeds of squirrel melon, which can cause vomiting and severe diarrhea in humans or animals after ingestion. Because of this, the seeds of squirrels are also used in laxatives.
The mechanism of the spray melon outbreak is somewhat similar to a pressure cooker. As the fruit matures, the tissue surrounding the seed begins to break down, forming mucilage. The process of gradually increasing mucus will continue to accumulate pressure inside the fruit, and finally erupt. Spraying melon can scatter the seeds to a distance of 1-6 meters.
Orina is a small cruciferous plant. Its pods burst rapidly when fully ripe, shooting seeds around in less than 3 milliseconds.
Scientists have found that the pericarp of broken rice chestnuts contains a large amount of lignin, which is mainly distributed in the endocarp layer, and the distribution is asymmetric. Lignin is a very hard organic polymer. The large amount of lignin contained in the endocarp makes the endocarp much harder than the exocarp of the pod. Microscopic imaging of a cross-section of the fruit flap revealed that the lignin in the endocarp is connected to each other like the hinges of a cabinet door, arranged in a curved plane. The curved surface helps maintain the shape of the petal (like a cyclist’s magic leggings), while also allowing the petal to build up stress. As the seeds in the pod grow, the petals accumulate more and more stress. When the seeds flatten the curved surface made of lignin, the fruit petals can no longer maintain their original shape, shrink violently, and instantly release all the stress accumulated before.
Native to Mesoamerica, root arundel, a well-known member of the Acanthaceae family, is also a “blast” plant. The most interesting thing about this plant is that the elongated seed pods of the root ash will “explode” and bounce off the spot when exposed to water. The immature seed pods are green and will not “explode” when exposed to water. When the color of the seed pods gradually turns from green to brown, it indicates that they have completed the preparation before “explosion”. The connecting part of the seed pod will lose its strength when exposed to water, which may be the mechanism that triggers the “explosion”.
After the seed pod is split, you can see some curved hard wires inside, which are the structures that provide kinetic energy for the “explosion” of the seed pod. When the strength of the connection part of the seed pod weakens when it encounters water, these hard filaments will snap the two petals of the seed pod apart. This is the secret of the “explosion” of the root Luli grass when it encounters water.