Desmodium Gyrans the dancing plant

Codariocalyx motorius - formerly Desmodium gyrans.

Codariocalyx motorius, known as the telegraph plant, dancing plant, or semaphore plant, is a tropical Asian shrub, one of a few plants capable of rapid movement; others include Mimosa pudica, the venus flytrap and Utricularia...

Much has been said on the Internet about this curious plant, whose scientific name is Desmodium gyrans, but it is better known by its other names: telegraph plant or… dancing plant.

But how true is it that he can dance? Does he really dance, or is it that we think he dances? We'll find out below.

The truth is that, unfortunately, he does not dance. There are some plants capable of rapid movements. Some of them are the Mimosa pudica that closes the leaves when an insect touches them, or the carnivorous plant Dionea better known as Venus flytrap, which closes its traps to get some food.

Our protagonist today, move its leaves every 3-4 minutes. In fact, in the description of some videos uploaded to YouTube, it is specified that the speed of their recording is increased.

Plants live on a different time scale. It is something logical and normal that, when we see a plant capable of making rapid movements, our brain interprets it as that the plant can dance. But if you have a chance, do the test. Look at the Desmodium gyrans with music, and then without music. You will see that it makes the same movements.

Of course, that does not mean that we cannot put music to our plants. Of course it is possible. Our elders did it, and even today they say that this way they will grow stronger and more vigorous.

For those who want to have this curious plant in their home, tell them that it is a tropical plant, whose origin is in the warm and humid jungles of Asia.

It doesn't grow much, maybe 50-60cm tall, which makes it a great plant to have in a pot. We must place it in a semi-shady place, avoiding direct sun.

Plants aren't generally known for their speed. They tend to move at rates we simply can't perceive. The few species that exhibit rapid movements such as the sensitive plant (Mimosa pudica) and the Venus fly trap (Dionaea muscipula) have become quite famous as a result. Such movements happen in fits and bursts. These plants certainly cannot maintain such activity. However, there is another plant out there whose activity puts these other plants to shame.

Meet the telegraph plant. It has gone by a handful of scientific names since its discovery (Desmodium motorium, D. gyrans, Hedysarum gyrans, Codariocalyx motorius) but that's not why its famous. This Asian legume is renown for its maneuvers. Its compound leaves are surprisingly active organs. The larger terminal leaflets move up and down throughout the course of a day but its smaller lateral leaflets exhibit rhythmic movements on the scale of minutes.

Perhaps most famously, the leaflets show an increase in movement when exposed to music. Search the web and you will find lots of videos of the telegraph plant "dancing" to a variety of musical styles. Though entertaining, music is not why this plant moves. Having evolved long before music was ever invented, its movement must have its roots in something a bit more natural. However, despite how popular such motion has made this species over the past few centuries, their its function has remained a bit of a mystery.

Before we get into the theories, let's take a closer look at exactly how this plant moves. At the base of its leaflets there sits a ring of cells called the "pulvinus." They act a bit like water balloons and thanks to some dedicated work, it has been found that, when stimulated, these cells can quickly move water in and out via osmosis. This causes the cells to either swell or deflate and this is where the movement originates. Now, onto the why...

A relatively recent opinion piece puts forth some of the most interesting theories on telegraph plant movement yet. The author suggests that leaflet movements are defensive in nature. They believe that the leaves could be mimicking butterfly (or some other winged arthropod movements). In doing so, it may convince gravid female insects that this individual plant is already occupied. Such strategies do indeed exist in some plant species, though via physical adornments rather than movements. Another theory this author puts forth is that their movements could also attract potential predators. By mimicking the movement of a tasty insect, it could entice birds to come in to take a closer look. Once there, they could easily find other herbivores hiding on the plant.

Another possibility related to defense is that the movements are meant to deter herbivory altogether. Studies on other plants have shown that some species can actually detect the vibrations of an insect chewing on leaves, which signals to the plant to uptick the production of defense compounds. Perhaps when sensing vibration, the telegraph plant increases its movements to knock away a hungry insect. Certainly a moving meal is less appealing than a stationary one. This is also thought to be the reason for rapid leaflet closure in sensitive plants. Hungry insects have a hard time hanging on to a plant when the leaf suddenly collapses from underneath it.

Another hypothesis is that these movements are meant to increase sun exposure. It has been discovered that far from only responding to music, the leaflets move throughout the day depending on temperature. When temperatures are low, leaflet movements are more vigorous. They eventually slow down if temperatures are high enough. This hypothesis is bolstered by the fact that movements cease once the sun goes down. In a sense, the leaflets seem to be using temperature as a means of detecting whether or not they are getting as much sun on them as possible.

In reality, it very well could be a mix of these ideas. Natural selection works like that. In the end, movement of the leaflets has certainly benefited the telegraph plant whether it be fore defense or just to take advantage of as much sun as possible. Despite centuries of popularity, this awesome little legume still has some secrets tucked away and I kind of like that about it.