I was introduced to this plant for the first time in 2013 by two of my students when we walked along the road at the Chokyi Gyatso Institute in Dewathang, Eastern Bhutan. I was surprised to see the behavior of the plant and how it reacted with a gentle touch on it. It closed up and contracted its leaves. The students asked me what the name of the plant was in English and why the leaves are closed up. I neither knew the name nor the scientific reasons behind the closure of the leaves. I said, “sorry and I don’t know.’’ This plant grows abundantly in and around Chokyi Gyatso Institute. When we saw this plant, I was warned by those two students that ‘’we will accumulate bad karma if we play with the plant.’’ I asked them, why? And they said, they were told by their parents that the process of closing up is very difficult and hard work for the plant.
Recently, when I saw the same plant displayed for an exhibition at the Exploratorium in San Francisco, I was very excited to learn the scientific reason behind the behavior of this plant. I took time to read the label explanation and the plant is called mimosa.
Now, when I compare the reasons stated by my students and the scientific explanations that ‘’the opening and closing of the leaves take a lot of energy from the mimosa plants’’, it make sense to me logically what my students have explained to me.
The mimosa plants can respond differently to harmful versus non harmful touches through regulation of energy. Because of this, mimosas have evolved the ability to habituate to stimuli that aren’t harmful. This means the plant is learning in many ways i.e. which types of touches will hurt it and which won’t.
What is actually happening with the mimosa when it closes up? The mimosas hold up their stems and leaves from the inside, using balloon like sacs filled with water. Our touch activates tiny receptors on the surface of the leaf, which sends a signal to drain the water from the sacs and it closes up. If the plant doesn’t respond, it may be over stimulated and we can try and play with another plant. In the wild, these plants close up during rain, heavy wind or when touched by an animal.
Now, I have a gift of an answer to my students for their then gift of question to me and we will together explore and experiment the mimosas in Dewathang.