Students of Ethnobotany: A plant too shy to touch


Mimosa pudica plant. Photo from Wikimedia Commons by H. Zell.

Round 2 of Students of Ethnobotany continues with this post, which is no shy wallflower, by Michael Bo Zhang.

I do not know about you but when it comes to plants I tend to think of them as immobile living organisms. They cannot move parts of their bodies or move around like most animals can. That is, I held that thought until I came across a little shrub called the shy plant, shame plant, or sensitive plant.

Just as these names suggest, this little plant actually responds to touch or shaking by folding their small leaflets like it’s trying to avoid those actions! A very similar scenario would be a snail shrinking its head back into its shell when being poked in the head.

The scientific name given to this little plant is Mimosa pudica. It is a member of the Mimosaceae family. The shame plant is about the size of a typical potted plant that you would see in a garden. It is a perennial, dwarf shrub (about half a meter tall) that is native to the tropical regions of Mexico, Australia, and South America. Today the shame plant can be found in most tropical regions of the world but is mostly grown in India.

You may be wondering how and why does the shame plant fold their leaflets when being touched or shaken. Does it have nerves and muscles like animals do? The answer is not really. First of all the shame plant has two well-known movements. One movement is called the seismonastic movement. Stimuli such as touching, shaking, or change in temperature would make the cells located in the stem respond by releasing chemicals that would make the leaflet cells lose turgor pressure and ultimately shrink.  The shrinking of the cells is what causes the leaflets to fold up. The sensory ability of the plant for different stimuli is achieved through chemical, electrical, and hydrodynamicaltransductions. The second type of movement is called nyctinastic movement. Nytinastic movement is periodical and is controlled by the plant’s biological clock. This causes the shame plant to fold its leaflets during night time and reopens them when light is present.


Leaflets close due to touch. Photo from Wikimedia Commons by H. Zell.

In addition to bringing curiosity to our eyes, the shame plant is also an herb intensely used in Ayurvedic medicine that is traditionally practiced in India. This plant contains a wide variety of natural chemicals that provide a surprising amount of disease cures. The shame plant has anti-bacterial, anti-venom, anti-depressant, analgesic, anti-inflammatory, wound-healing, and many other pharmacological properties. Different chemicals in different parts of the plant can be used to treat various illnesses. The roots of the shame plant taste bitter and contain chemicals that have wound-healing, anti-venom, anti-fertility, and anti-inflammatory activities. Notable illnesses that can be treated by the roots include urinary complaints, leprosy, gynecological disorders, dysentery, and more. The leaflets are used to treat urinary infections and hemorrhoids by extracting the juice from the leaflets or making pastes out of them. It isimportant to note that there are also several treatment properties that can only be obtained from the whole plant. The plant as a whole possesses anti-microbial, anti-fungal, anti-viral activities. With so many medicinal uses all packed into one small plant, no wonder the shame plant is so intensively used by practitioners of Ayurvedic medicine.
Reference List:

Ahmad H, Sehgal S, Mishra A, & Gupta R (2012). Mimosa pudica L. (Laajvanti): An overview. Pharmacognosy reviews, 6 (12), 115-24 PMID: 23055637

Sreedevi, A. and Santhoshi A.H.V. (2013). Pharmcological evaluation of Mimosa pudica for anti-inflammatory activity. Pharmacie Globale. 5(4)

Volkov AG, O’Neal L, Volkova MI, & Markin VS (2013). Morphing structures and signal transduction in Mimosa pudica L. induced by localized thermal stress. Journal of plant physiology, 170 (15), 1317-27 PMID: 23747058

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