Directional changes are called tropic movements. Tropic movements are the one which occurs in the direction of the stimulus. Positive phototropism is responding by bending towards the sunlight which can be seen in shoots. Negative geotropism is growing away from the ground which is also shown by shoots. Roots exhibit negative photo tropism by bending away from the light and show positive geotropism by growing towards the ground. Chemotropism is a movement of growth in plants in response to the chemical stimulus like the growth of pollen tubes towards ovules.
Non- Directional Movements
Non-directional movements are called nastic response and concerned to movements of plant parts. Nastic movements are independent of growth, and plant cells have to change their shape for this movement to occur. These changes take place in the opposite direction to the stimulus.