I remember while on a hiking trail in Kruger, the ranger told us something quite amazing: that plants could communicate with each other. “So if a kudu eats the leaves on a tree, that tree can send a warning to other trees by releasing chemicals into the air.
This stimulates them to produce a chemical that makes their leaves taste unpleasant,” he said. I thought that so clever. Now I have learned even more fascinating secrets about clever plants in a book called The Light Eaters by Zoë Schlanger. Take the mucuna vine that is pollinated by bats. Bats use echolocation to find their way at night so they can calculate the exact distance, size and shape of objects. Researchers wondered how bats knew to land only on those vine flowers whose nectar had not already been depleted by another bat. Turns out it’s because the vine is clever. It has a curved petal-like appendage on the side of the flower that reflects the bat’s sonar loud and clear, so the bat heads straight to the vine flower. While it’s drinking the nectar, the plant releases its pollen onto the bat’s back. Then the bat flies off to another flower, inadvertently carrying the pollen to pollinate the next vine flower. Here’s the astonishing bit: once the vine flower has released its pollen, it no longer needs to attract bats, so it lowers the petal appendage on a plant hinge, packing away its “sonar equipment”. The next bat flies right past it. Extraordinary. Then there are plants that react to caterpillars eating their leaves. As the book points out, plants have no ears but can “hear” by picking up vibrations. Experiments have shown that they recognise the vibrations of munching caterpillars, and take action. Some create nasty-tasting tannins in their leaves, but the reaction of the tomato plant is quite scary. “The tomato plant will inject something into its leaves that will make the caterpillars look up from their chewing and turn to eye their fellow caterpillars. Soon the caterpillars begin to eat each other,” Schlanger writes. Like something out of a horror movie. I like the plant in Brazil that plants its own seeds. Once Spigelia genuflexa plants have been pollinated and developed fruit, they bend their stems until the fruit touches the ground. “They push down until it is buried in the soft moss. The plant has planted its own seeds.” Plants also communicate underground through large networks of fungi known as the “wood wide web”. Plant scientist Sven Batke says this network allows plants to share resources like water, food and information. “Over 80% of plants are believed to be connected, making it one of the oldest communications systems in the world.” So are plants intelligent? Most scientists will answer “no”. They have no brain or nervous system. I don’t think the “intelligent” label matters much. It is enough to recognise that plants have astonishing abilities. For me the cleverest plant characteristic of all is their ability to stick their roots in the ground, their branches in the air and make food from the sun.
