The movement or growth of any part of a plant in response to an external stimulus is called tropism or tropic movement. Tropic movements are of three types :
1. Phototropic movement (Phototropism) : The movement of a plant in response to the stimulus of light is called phototropism. E.g. the shoot system of any plant responds towards the stimulus of light i.e. it grows in the direction of source of light.
2. Gravitropic movement (Gravitropism) : The root system of the plants responds to the stimulus of gravity. This movement is called as gravitropic movement.
3. Hydrotropic movement (Hydrotropism) : The root system of the plants responds to the stimulus of water. This movement is called hydrotropic movement.
4. Chemotropic movement (Chemotropism) : It is the movement of a plant part in response to certain chemicals. E.g. the growth of pollen tube towards the ovules.
1. Phototropic movement (Phototropism) : The movement of a plant in response to the stimulus of light is called phototropism. E.g. the shoot system of any plant responds towards the stimulus of light i.e. it grows in the direction of source of light.
2. Gravitropic movement (Gravitropism) : The root system of the plants responds to the stimulus of gravity. This movement is called as gravitropic movement.
3. Hydrotropic movement (Hydrotropism) : The root system of the plants responds to the stimulus of water. This movement is called hydrotropic movement.
4. Chemotropic movement (Chemotropism) : It is the movement of a plant part in response to certain chemicals. E.g. the growth of pollen tube towards the ovules.