VENUS HAS FEELINGS
Does the infamous flytrap have a memory, too,
“God gave us memories that we might have roses in December.” — J.M. Barrie, Courage, 1922 Last week I reported on the content of the fascinating new book What a Plant Knows. I talked about empirical evidence that plants see and smell. Today, I explore how a plant feels, hears and what it remembers.
The author, Daniel Chamovitz (danielchamovitz.com), director of the Manna Centre for Plant Biosciences at Tel Aviv University, has a writing style that even I can understand. This is not high-brow scientific information from an industry journal; it’s extraordinary stuff about real-world plants delivered in plain language with a sprinkling of humour.
WHAT A PLANT HEARS
know that a plant does not have ears, that is not the point. Some days when I am in my garden, the sounds of insects, songbirds, the wind passing through the trees, and the movement of water creates a “cyclical cacophony.” As the crickets chirp and the toads call out, one has to ask, “Do plants hear any of this?”
Chamovitz is clear that we actually lack real evidence that plants hear. We are much more certain that they see, smell and feel. However, that does not mean that your philodendron does not like the classical music that you play for it. Or that your amaryllis is not listening when you speak kindly to it.
Many experiments by scientists have occurred through the ages, with one conclusion: Plants do not hear. As Chamovitz concludes in this chapter, “(plants) may be deaf, but they are acutely aware of where they are, what direction they are growing and how they move.” So let’s move on.
HOW PLANTS FEEL
Here is an experiment that all of us have taken part in at one time or another: Gently brush the sensitive hairs of the Venus flytrap flower and watch it shut its trap, like magic. While this may be proof enough that some plants feel, there is much more to the story than that, according to Chamovitz.
Plants, like the burr cucumber, are up to 10 times more sensitive than we are when it comes to touch. Vines of this aggressive plant can feel the weight of a quarter of a gram. This is enough to induce the vine to start winding itself around a nearby object. For the burr cucumber, that is precisely the point. Being able to grab on to an object with its aggressive tentacles is what this plant does best.
Back to the Venus flytrap. Charles Darwin became the foremost expert in the field of carnivorous plants. His extensive experiments revealed much about plants that had, until that time, been accepted as a great mystery.
How does a Venus flytrap know that the insect crawling up to the flower is the right size for consumption? When does it know to shut its trap around the unsuspecting insect?
The answer is that an insect has to touch the hairs on the trap at both ends.
Not only that, but the movement from the fore-hairs to the aft-hairs must take place over a precise period of time, indicating to the plant that the insect is the right
Gently brush the sensitive hairs of the Venus flytrap flower and watch it shut its trap, like magic
size for consumption. Otherwise the trap simply does not shut.
APLANT KNOWS ITS PLACE
Perhaps the most fascinating finding of all is that plants actually know where they are. The recently popular “upside-down tomato planter” proves that a tomato can grow upside down quite nicely. Not only that, the green part of the plant continues to reach upwards and the roots continue to move deep into the vertical soil. Simply put, the tomato plant knows what to do regardless of the abuse that we heap on it. This is called proprioception. We have the same ability as a plant does: to know where our body parts are relative to each other at any one time without having to see or touch them. This is what gives us the ability to walk and the ability for bean plants to grow in the weightlessness of outer space. To a large extent, a plant has the ability to understand its general place in this world thanks to the innate ability of its roots. At the root tips, a hormone called auxin exists. While many hormones exist in a plant, none is more prevalent than this one. “While different stimulations activate different plant senses, many of the plant’s sensory systems converge on auxin, the movement hormone,” Chamovitz reports.
MEMORY
A plant’s ability to catalogue experience in a memory may be hard for us mere mortals to fathom. However, when a pea plant is exposed to light and a tendril stim- ulated by rubbing it with a finger, the tendril will coil around it, as if holding on to the finger. Like a baby who grips your finger when you place it in their palm. The interesting thing is that when the same pea plant is placed in a dark room two hours later, it spontaneously coils around your finger without having to rub it. One more new word for you: vernalization — the period of cold that is required to trigger the flowering of a lilac and other winterhardy plants. How does a plant know that spring is spring and not fall, when day length is similar? The answer: It remembers the cold that it experienced only a few weeks prior.
Moreover, memories are handed down from one generation of plants to another. It is fascinating to learn that plants not only encode their experience with cold weather, but also other conditions that create stress. The next generation of plants reacts similarly to the parent, building into their DNA the new code required for successful existence and procreation.
All of this is to say that plants have their own methods for smelling, seeing and feeling. It’s interesting to know that the oak that you touch this morning will remember your touch, even if it will not remember you.
“You, on the other hand, can remember this particular tree and carry the memory of it with you forever,” says Chamovitz.
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