Mark Cullen
FOR BRANT NEWS

“God gave us memories that we might have roses in December.” ~ J.M. Barrie, Courage, 1922

Last week, I reported on the content of a fascinating new book titled 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, 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 is extraordinary stuff about real-world plants delivered in plain language with a sprinkling of humour.

What a plant hears

I know that a plant does not have ears – that is not the point. Some days when I am in my garden listening to the sounds of insects, song birds, the wind passing through the trees above and the movement of water from my water feature, I ask myself: “Do plants hear any of this?”

Chamovitz is clear that we lack real evidence that plants do “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.

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 the author.

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 of it.

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 through its internal sensors that the insect is the right size for consumption. Otherwise, the trap simply does not shut. When it rains, a Venus flytrap does not shut. Now we know why.

A plant 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 we heap on it. This is called “proprioception.”

To a large extent, a plant has the ability to understand its general place in the world thanks to the innate ability of the plant roots. At the root tips exists a hormone called auxin. While many hormones exist in a plant, none are more prevalent than this one. Chamovitz reports: “While different stimulations activate different plant senses, many of the plant’s sensory systems converge on auxin, the movement hormone.”

All of this is to say that plants have their own methods for smelling, seeing and feeling. While they are markedly different from our own, it is important to know that the oak that you touch this morning will remember your touch, even if it will not remember you.

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