Enduring the cold, icy snap of this week (January!) made me think of the plants in my garden. While I can retreat to a warm house or could travel south for a few weeks of winter to warmer countries, plants are rooted to their spot, unable to move anywhere more suitable, whatever the weather conditions. This meant that they had to adapt and learn to be resilient. The latest scientific research is concentrating on the legacy of shared genomes that enables plants to respond to their environments. We are now discovering plants’ sensory attributes, their complexity and perceptiveness. As technology progresses, through the scientific experiments we can prove that plants can see, smell, feel, be aware of their surroundings, and remember. This leads to the logical conclusion that plants have some kind of intelligence. The comparison of plant abilities to adopt to their environment to our own senses does offer an explanation how plants survive although not being able to move. We have to accept that there is evidence of plants’ consciousness and basic awareness. A shared genetic past explains the reasons of the separate evolution that started two billion years ago. It evolved from the single organism that was our, and also both plants and animals, ancestor. Plants can think.
I am one of those gardeners who talk to the plants in their garden, and however odd it may seem to others, I can see the positive results of such an interaction. I don’t discuss politics or philosophy with my plants, but I do mention the weather, check that they look happy, have enough light, water and feeding, compliment them on their beauty, and while providing what is needed, all the time I am giving the plants a running commentary on the proceedings. Recently, a study published on the website BioRxiv provided more evidence that plants can respond to sounds. On hearing the buzz of approaching bees, flowers respond by producing sweeter nectar. The bees visit those flowers more often, increasing the amount and area of the pollen distribution. When the recording of buzzing bees was played to evening primrose flowers, the sugar concentration in the nectar rose by 20% within three minutes. In urban environment it is common to find roots of trees wrapped over the water pipes. Originally it was thought that the roots move towards the pipes because of water leaks, but when no leaks were discovered, the logical explanation was that the trees can hear the water moving in the pipes. Plants can hear.
In one of my previous posts, ‘Love Letter to Trees’, I wrote about Africa’s acacias trees and their defence system that prevents giraffes, their main ‘enemy’, from stripping their branches bare. When one tree’s leaves are being munched by passing giraffes, it releases a powerful tannin through surface pores. The smell is carried downwind and the next acacia tree, even some distance away, picks it up and automatically releases its own tannin (tasting bitter), in response to the message. Giraffes will never feed in the direction of the wind, if they can help it, because all the acacia trees would exude the tannin. Instead, they will be browsing against the wind on unsuspecting acacias. It is a remarkable case of communication between the trees. As plants don’t have a brain, and therefore there is no connection between the receptor (the nose) and a brain, like there is in humans, they do have the ability to smell through stimuli. We all use bananas to help to ripen other fruits. We could only understand how when a scientist discovered that a molecule called ethylene was involved. Any fruit treated with pure gas ethylene would become ripe in a short time. The unripe fruit, say apples, can smell ethylene exuded by bananas and ripen. Plants can smell.
Those who garden or have house plants know that all plants bend toward the light. This is called phototropism. Darwin’s contemporary, Julius von Sachs, discovered that blue light is the primary colour that makes plants react to light. Darwin’s later experiments proved that plants bending toward the light was not due to photosynthesis as was believed, but by some inherited sensitivity. He also found that it was always the tip of the plant which acted that way, and not the part that was bending. His famous experiments with seedlings proved that when light hits the tip of the plant, it can see it and then passes this information to the middle part that then bends towards the light. Plants can see.
Plants make sugars through photosynthesis, then turn them into protein and complex carbohydrates. But they are wholly dependent on their environments for the minerals necessary for their growth and survival. Their needs are extensive as they must have nitrogen, phosphorus, potassium, calcium and magnesium. They also require traces of iron, zinc, copper, nickel and a few others to have adequate nutrition. The process of using all these nutrients is very complex. Some of those nutrients are an essential part of the process of photosynthesis, called water-splitting. A by-product of this process is that two atoms of oxygen pair up to create O2 which is realised into the air as the oxygen that humans breathe. Without this process we could not breathe. It is therefore of utmost importance to us too that plants can find the right nutrients by tasting the soil around them. Those tasting receptors are found in the membranes of the root cells. Scientists now know that plants know how many nutrients they need, depending on the conditions around them. Technology allows us to hear the water being delivered from plant roots via the xylem, the plants’ water veins, with a listening device placed against the trunk of a tree. The absorption of nutrients is under strict biological rule. A plant decides which minerals are to be carried up with water into the branches and leaves after tasting each one in the soil. Plants can taste.
Plants know when they are being touched. Climber plants respond to the touch of any object they touch by wrapping themselves around it. I have roses growing through apple trees. Carnivorous plants that feed on insects, like Venus flytrap, are incredibly speedy in their mechanism of shutting their prey in, it takes one-tenth of a second. The success of those plants comes from their ability to feel the insects touching their ‘skin’. Mimosa plants are famous for drooping their leaves when touched and we even use the term ‘mimosa-like’ pertaining to oversensitive people. Scientists discovered that persistent touching of plants resulted in reduced growth of leaves. Plants also react to wind and rain. Plants can feel.
As we are continuously discovering astonishing facts about plants, one thing is certain: there is much more to find and understand. We are gravitating towards feeding more on foods derived from plants, and that expanding and illuminating knowledge is therefore of vital importance. Plants matter.