Nastic movement is non directional movement while tropic movement is directional movement with responce to any stimulas like water ,touch,sunlight ,etc.
→ Nastic movements are non directional responses to stimuli such as temperature and heat. … → Tropic movement is the response to stimuli that comes from one direction. → It is a directional movement. → If the movement of the plant part is towards the stimulus, then it is known as positive tropism .
Response to stimulus towards a certain direction is called tropism movement
The non directional movement to stimulus is nastic movement

\tTropic movementsNastic movements1. It can be easily observed in stems and roots.1. It is clearly observed in bilaterally symmetrical organs such as leaves and petals of flowers.2. It is due to unilateral stimulus which causes unequal growth on the two sides of a stem, root and tendril.2. The movements occur due to stimulus of light and temperature.3. Movement is related to stimulus, i.e., plant organs either move towards source of stimulus or away from it. Stimuli which causes movements in plants are gravity, light, touch, water and chemical substances.3. Opening and closing of flowers of evening primrose and tobacco at the night and day respectively. This is due to unequal growth.4. Example: Bending of root towards gravity and shoot towards light.4. Example: Leaves of ‘touch-me-not’ plant bend and droop on touching.\t
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