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Mimosa pudica (from "shy, bashful or shrinking"; also called Sensitive Plant), is a creeping annual or perennial herb often grown for its curiosity value: the compound leaves fold inward and droop when touched or shaken, re-opening minutes later. The species is native to South America and Central America, but is now a pantropical weed.
The stem is erect in young plants, but becomes creeping or trailing with age. The stem is slender, branching, and sparsely to densely prickly, growing to a length of 1.5 m (5 ft). The leaves of the mimosa pudica are compound leaves.
The leaves are bipinnately compound, with one or two pinnae pairs, and 10-26 leaflets per pinna. The petioles are also prickly. Pedunculate (stalked) pale pink or purple flower heads arise from the leaf axils. The globose to ovoid heads are 8–10 mm in diameter (excluding the stamens). On close examination, it is seen that the floret petals are red in their upper part and the filaments are pink to lavender. The fruit consists of clusters of 2-8 pods from 1–2 cm long each, these prickly on the margins. The pods break into 2-5 segments and contain pale brown seeds some 2.5 mm long. The flowers are pollinated by the wind and insects.<ref name=Forest>"Mimosa pudica L.". US Forest Service. http://www.fs.fed.us/global/iitf/pdf/shrubs/Mimosa%20pudica.pdf. Retrieved 2008-03-25. </ref> The seeds have hard seed coats which restricts germination.<ref>Chauhan, Bhagirath S. Johnson; Davi, E. (2009). "Germination, emergence, and dormancy of Mimosa pudica". Weed Biology and Management 9 (1): 38–45. doi:10.1111/j.1445-6664.2008.00316.x </ref>
Mimosa pudica is well known for its rapid plant movement.
Like a number of other plant species, it undergoes changes in leaf orientation termed "sleep" or nyctinastic movement. The foliage closes during darkness and reopens in light.<ref> Raven, Peter H.; Evert, Ray F.; Eichhorn, Susan E. (January 2005). "Section 6. Physiology of Seed Plants: 29. Plant Nutrition and Soils". Biology of Plants (7th ed.). New York: W. H. Freeman and Company. pp. 639. ISBN 978-0-7167-1007-3. OCLC 56051064. http://books.google.com/?id=8tz2aB1-jb4C&pg=PA58. </ref>
The leaves also close under various other stimuli, such as touching, warming, blowing, or shaking. These types of movements have been termed seismonastic movements. The movement occurs when specific regions of cells lose turgor pressure, which is the force that is applied onto the cell wall by water within the cell vacuoles and other cell contents. When the plant is disturbed, specific regions on the stems are stimulated to release chemicals including potassium ions which force water out of the cell vacuoles and the water diffuses out of the cells, producing a loss of cell pressure and cell collapse; this differential turgidity between different regions of cells results in the closing of the leaflets and the collapse of the leaf petiole. This characteristic is quite common within the Mimosoideae subfamily of the legume family, Fabaceae. The stimulus can also be transmitted to neighboring leaves. It is not known exactly why Mimosa pudica evolved this trait, but many scientists think that the plant uses its ability to shrink as a defense from predators. Animals may be afraid of a fast moving plant and would rather eat a less active one. Another possible explanation is that the sudden movement dislodges harmful insects.
Taxonomy and nomenclature
Mimosa pudica was first formally described by Carl Linnaeus in Species Plantarum in 1753.<ref name></ref> The species epithet, pudica, is Latin for "bashful" or "shrinking", alluding to its shrinking reaction to contact.
The species is known by numerous common names including
- sensitive plant<ref name=GRIN>"Mimosa pudica L.". Germplasm Resources Information Network (GRIN). United States Department of Agriculture, Agricultural Research Service, Beltsville Area. http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?24405. Retrieved 2008-03-22. </ref>
- humble plant<ref name=GRIN/>
- shameful plant<ref name=GRIN/>
- sleeping grass<ref name=Usambara/>
- touch-me-not<ref name=GRIN/>
Other non-English common names include morí-viví or moriviví <ref name=Ombrello>"The Sensitive Plant". Union County College Biology Department. http://faculty.ucc.edu/biology-ombrello/POW/sensitive_plant.htm. Retrieved 2008-03-22. </ref> (Dominican Republic and other Spanish-speaking Caribbean islands, roughly translating to "dies then lives"), Makahiya (Philippines, with maka- meaning "quite" or "tendency to be", and -hiya meaning "shy", or "shyness"), and mate-loi (false death) (Tonga). In Urdu it is known as CHui-Mui. In Bengali, this is known as Lojjaboti, the shy virgin. In Indonesia, it is known as Putri Malu (Shy Princess). In Malayalam it is called "Thottavaadi" (wilts by touch). In Marathi it is called "LazaLu" (shy). In Tamil, it is called Thotta-siningi (cry-baby). In Malaysian it is called Pokok Semalu (shy plant). In Myanmar (Burma) it is called Hti Ka Yoan which means "crumbles when touched".
Mimosa pudica is native to South America and Central America. It has been introduced to many other regions and is regarded as an invasive species in Tanzania, South Asia and South East Asia and many Pacific Islands.<ref name=Usambara>"Mimosa pudica". Usambara Invasive Plants. Tropical Biology Association. http://www.tropical-biology.org/research/dip/species/Mimosa%20pudica.htm. Retrieved 2008-03-25. </ref> It is regarded as invasive in parts of Australia and is a declared weed in the Northern Territory,<ref>"Declared Weeds in the NT - Natural Resources, Environment and The Arts". Archived from the original on 2008-02-26. http://web.archive.org/web/20080226133716/http://www.nt.gov.au/nreta/natres/weeds/ntweeds/declared.html. Retrieved 2008-03-25. </ref> and Western Australia although not naturalized there.<ref>"Declared Plants- Sensitive plant common (Mimosa pudica)". http://agspsrv95.agric.wa.gov.au/dps/version02/01_plantview.asp?page=7&contentID=60&. Retrieved 2008-03-25. </ref> Control is recommended in Queensland.<ref name=Biosecurity>"Common Sensitive Plant". Invasive plants and animals. Biosecurity Queensland. http://www.dpi.qld.gov.au/cps/rde/xbcr/dpi/IPA-Common-Sensitive-Plant-PP38.pdf. Retrieved 2008-03-25. </ref> It has also been introduced to Nigeria, Seychelles, Mauritius and East Asia but is not regarded as invasive in those places.<ref name=Usambara/> In the United States of America, it grows in Florida, Hawaii, Virginia, Maryland, Puerto Rico, Texas, and the Virgin Islands.<ref>Distribution of Mimosa pudica in the United States of America Natural Resources Conservation Service, United States Department of Agriculture.</ref>
The species can be a troublesome weed in tropical crops, particularly when fields are hand cultivated. Crops it tends to affect are corn, coconuts, tomatoes, cotton, coffee, bananas, soybeans, papaya, and sugar cane. Dry thickets may become a fire hazard.<ref name=Forest/> In some cases it has become a forage plant although the variety in Hawaii is reported to be toxic to livestock.<ref name=Forest/><ref>"Mimosa pudica (PIER species info)". http://www.hear.org/pier/species/mimosa_pudica.htm. Retrieved 2008-03-25. </ref>
Mimosa pudica can form root nodules that are inhabitable by nitrogen fixing bacteria. The bacteria are able to convert atmospheric nitrogen, which plants can not use, into a form that plants can use. This trait is common among plants in the Fabaceae family.
In cultivation, this plant is most often grown as an indoor annual, but is also grown for groundcover. Propagation is generally by seed.
Its extract immobilizes the filariform larvae of Strongyloides stercoralis in less than one hour.<ref>Robinson RD, Williams LA, Lindo JF, Terry SI, Mansingh A. (1990). "Inactivation of strongyloides stercoralis filariform larvae in vitro by six Jamaican plant extracts and three commercial anthelmintics". West Indian Medical Journal, 39(4):213-7.</ref> In contemporary medicine, Mimosa pudica is being investigated for its potential to yield novel chemotherapeutic compounds. It contains an alkaloid called mimosine, which has been found to have potent antiproliferative and apoptotic effects.<ref>"Antiproliferative effect of mimosine in ovarian cancer". Journal of Clinical Oncology. http://meeting.ascopubs.org/cgi/content/abstract/23/16_suppl/3200. Retrieved 2010-01-13. </ref>
Aqueous extracts of the roots of the plant have shown significant neutralizing effects in the lethality of the venom of the monocled cobra (Naja Kaouthia). It appears to inhibit the myotoxicity and enzyme activity of cobra venom. <ref>http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T8D-4313NPH-B&_user=10&_coverDate=04%2F30%2F2001&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1408893239&_rerunOrigin=google&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=942e2b5c5b4c53c56c704be83fc41bf2</ref>
- A list of notable chemical compounds found in Mimosa pudica
- View occurrences of Mimosa pudica in the Biodiversity Heritage Library
- "Sensitive Plant" page by Dr. T. Ombrello
- Page about nyctinasty and leaf movement of Mimosa pudica by John Hewitson
- Youtube video: Mimosa Pudica
- Indiana.edu "Plants in motion" videos of Mimosa pudica: 1 and 2
- "Video:MIMOSA PUDICA SENSITIVE:guide de culture". Ethnoplants.com. http://www.ethnoplants.com/mimosa-pudica. Retrieved 2009-10-12.