Mimosa pudica commonly known as sensitive, touch-me-not, humble or shameful plant is from the pea family Leguminosae. It has about 300 species and is native to Central and South Americas but has become a pan tropical weed. It is a prostrate creeper with reddish-brown, prickly, hairy, cylindrical stems. . Mimosa pudica is a shrubby plant that can grow up to 18 inches outdoors. Its flowers resemble pinkish/purplish puffs that have ½ inch-long pods containing 3 to 4 seeds. It was introduced to other countries mainly as an ornamental plant and can still be found on sale . However, it has become a pest in forest plantations, cropland, orchards and pastures.
What make the Mimosa pudica unique are its nysctinastic and seismonastic movements. Nystinastic movement is where the leaflets fold together and the whole leaf droops downward at night until sunrise. Seismonastic movements are when touched, shake, warmed or subjected to chemical or electrical stimuli, the leaflets fold together, and the whole leaf will droop temporarily . These characteristics are the reasons why Mimosa pudica got the names of shameful plant or humble plant because it seems to be shying away from any kind of stimuli.
Mimosa pudica occurs in croplands, orchards, pastures, mowed areas, roadsides, areas disturbed by construction, moist waste ground, open plantations and weedy thickets. It does not like the shade nor compete with tall vegetation. It does not grow under forest canopies. It is primarily found in low nutrient soils where the competition with other plants is minimal. It does, however, form a dense ground cover which prevents other species from reproducing. This weed has become a serious concern in fields of corn, soybeans, tomatoes, upland rice, cotton, bananas, sugarcane, coffee, oil palms, papayas, coconuts and rubber in many tropical areas.
The seeds and other parts of Mimosa pudica have been used as a medicinal plant in many regions. It contains mimosine, and its extracts have been shown as a moderate diuretic in scientific trials. It also depresses duodenal contractions similar to atropine sulphone, promotes regeneration of nerves and reduces menorrhagia. It also demonstrates an antidepressant activity in humans. Its root extracts are reported to be a strong emetic. South East and South Asian countries have used M. pudica as a traditional/alternative medicine .
References
Global Invasive Species Database. Mimosa pudica (herb). 4 October 2010. http://www.issg.org/database/species/ecology.asp?si=1002&lang=EN. 28 July 2014.
Ombrello, T. The Sensitive Plant. n.d. http://faculty.ucc.edu/biology-ombrello/pow/sensitive_plant.htm. 28 July 2014.
