Thursday, 13 December 2012

Natural Defense In Plants

Plants have specific characteristics to protect themselves from enemies. Mimosa plants fold their leaflets when touched.  The leaves also close under various other stimuli, such as touching, warming, blowing or shaking.  This types of movement 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 stem are stimulated to release chemicals including potassium ions which force water out the cell vacuoles and the water diffuses out 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.

      Mimosa prior to a touch.             


Mimosa with folded-in leaves immediately after a touch.


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