Imagine a plant that acts shy! The Sensitive Mimosa (Mimosa pudica) appears to sulk away when you touch it—but how is behaviour in a plant possible? In this lab, you will peer into the secret messages to observe how touch information is relayed inside this wonderful plant.
Meet the Sensitive Mimosa, an intriguing tropical plant whose name literally means “shy.” Growing naturally in sunny, humid areas from Brazil to Thailand, this plant has charmed people with its rapid and almost animal-like responses. When gently touched, its delicate leaf segments close up neatly, returning to normal after a short while if given plenty of bright light. A firmer touch, however, can prompt the entire leaf stem to drop suddenly, which may help by exposing its thorns and startling hungry herbivores.
In today’s experiment, you’ll have the chance to replicate these distinctive behaviors and test the plant’s recovery time firsthand. Try it before we begin. How quickly will your Mimosa spring back into action under good lighting conditions? Your observations will help unlock some fascinating secrets of plant behavior!
Mimosa pudicas can be found from online resellers as small seedling plants. You can try to grow from seeds too, but it can be challenging (untreated seeds have a hard coat and only about 1 in 7 germinate; nicking the coat or soaking seeds in hot water helps a lot).
Note the timing of your recorded waveforms with the plant’s behavior to deduce the involvement of ion channels and water movement in the rapid leaf closure.
Examine the shape of the action potentials, noting the characteristic shape. How does this compare to that of a neuron or muscle action potential?
