"A Sensitive Plant in a garden grew,
And the young winds fed it with silver dew,
And it opened its fan-like leaves to the light.
And closed them beneath the kisses of Night."
This poem by Percy Bysshe Shelley meanders on for 311 lines, and I recommend taking the time to read it not only for its lyric beauty, but also for its description of the senses of a garden.
What is the "sensitive plant" of which Shelley writes?
The most famous sensitive plant is Mimosa pudica which is native to South and Central America, but is now grown worldwide as an ornamental plant because of its fascinating moving leaves. The Mimosa’s leaves are hyper-sensitive to touch, and if you run your finger down one of its leaves, all the leaflets rapidly fold inward and droop. They reopen several minutes later, only to rapidly close once more if you touch them again. The name “pudica” reflects this drooping movement. It means “shy” in Latin. The plant is also known throughout many regions as “the sensitive plant”. Its unusual behavior is referred to as “false death” in the West Indies, it is referred to as the “don’t touch me” plant in Hebrew, and in Bengali it is called the “shy virgin”.
The drooping and opening action that is characteristic of the Mimosa is regulated by electricity. This was noticed by Sir Jagadish Chandra Bose, a noted physicist turned plant physiologist from Calcutta, India, back at the beginning of the 20th century. Bose reported to the Royal Society in 1901 that touch initiated an electric action potential which radiated the length of the leaf resulting in the rapid closing of the Mimosa leaflets.