Question

Touch me not’ shows ________movement.
A. Nastic
B. Tropic
C. Both A and B
D. None of the above

Answer 1

Hint: Nastic movements occur as the response to a stimulus, such as coming in contact with a foreign body, wind, water, and so on. Tropic movement is a biological phenomenon that indicates the growth of a biological organism, in response to an environmental stimulus. As we know that nastic movements are the ones shown by Mimosa pudica.

Complete answer:
Nastic movements as mentioned above occur as a response to a stimulus.
These movements are shown by different parts of the plant like stigmas, stamens, and leaves.
To be specific about the ‘Touch me not’ (Mimosa pudica) plant, seismonastic movements are significantly shown.
Changes take place in the orientation of its leaves which is termed as “sleep” or called the nyctinastic movement.
The closure of leaves is called foliage. It occurs in the darkness which then reverses during the daylight.
Touching, blowing, or shaking can also cause the same types of movements.
The occurrence of the movement is primarily due to the loss of turgor pressure in specific regions of the cell. Turgor pressure is the force applied by the water on the cell wall within the cell vacuoles and other cell contents.
Potassium ions are released by specific parts of the plant on disturbance, which forces out the water from the cell vacuoles, producing a loss of cell pressure. Thus, the cell collapses.
It makes a difference in turgidity between different regions of cells. The effect of turgidity on the closing leaflets and collapse of the leaf petiole.
So, the correct answer is “Option A”.

Additional Information:
Biophytum sensitivum and Neptunia oleracea are some of the other plants showing nastic movements.
Locomotion is shown by small plants and other naked protoplasmic bodies whereas movements of parts are shown by large plants.

Note:
Intensity of stimulus, the vigor, age of the plant, and the time elapsed since the last stimulus are the factors that influence the extent of seismonastic movement. The leaf of Mimosa is a compound leaf with four pinnae. Each of the pinnae has several numbers of small pinnules. The whole leaf droops down if the terminal pinnae are touched. This is because of the loss of turgidity of the lower portion of the pulvinus. Mimosa pudica loses its turgidity due to this reason.