The sensitive plant Mimosa pudica L. is a shrub or creeping annual, a member of the legume family of plants. It is a curiosity among plants because of its amazing ability to fold its leaves instantly when touched. Originally from South America, it is now found in tropical areas around the world and is called many different names.
The most common form of mimosa, Mimosa pudica, trails out on the ground, growing in crowded fields and alongside roads in the tropics. The thin stems creep up to 5 feet. Mimosa himalayana and Mimosa hamata are shrub varieties of mimosa growing to 5 feet tall and 3 feet wide.
The thin, branching stems of mimosa have slender leaves that grow on either side in the manner of ferns. Stalks growing from the axil, the point where the petiole, or stem, of the leaf attaches to the stem itself, bear flowers that are red on top with pink or lavender filaments. Although mimosa is sometimes cultivated as a botanical curiosity, it is considered difficult to grow. Since it obtains nitrogen from the air it can thrive in poor soil. It likes temperatures from 80 to 85 F.
When it is touched, mimosas fold their leaves instantly. The creeping variety grows among other tropical plants. When its leaves suddenly wilt, the slender, dark stems blend into the background, and the plant seemingly disappears. The botanical explanation for the instant wilting is that the touched plant sends chemical signals that empty the leaf cells of their water. This behavior may have evolved so that the plant could dislodge insects or hide from foraging animals. The leaves also fold at night.
The species name pudica is Latin for bashful or shrinking. Popular names in English are sensitive plant, bashful mimosa, humble plant, sleeping grass, tickle me, prayer plant, touch-me-not and shameful plant. Among the many foreign language names are makahiya (shy in Tagalog, a Filipino language), mati loi (false death, Tonga), morivivi (death and life, West Indies), hiti ka yoan (crumbles when it is touched, Myanmar), nikikumba (sleep in Sinhalese, a language of Sri Lanka) and thotta-singingi (cry baby, Tamil, also a language of Sri Lanka).
Mimosa is native to Central and South America. In is regarded as an invasive species in Queensland, Western Australia and Northern Territory in Australia plus East and Southeast Asia, many Pacific islands and parts of Africa.
Mimosa contains mimosine, an alkaloid that is asserted to have medicinal properties. The plant, which has a bitter, astringent taste, is used in India to treat diarrhea and amoebic dysentery. These and other alternative medicinal uses for the plant are based on anecdotal evidence and have not been tested by clinical trial.
There is confusion between Mimosa pudica and the large shrub or tree Mimosa tenuiflora that contains DMT (dimethyltyptamine) a psychoactive alkaloid. In parts of Brazil, DMT extracted from the bark is used to make a hallucinogenic tea. The plants are related but not the same.