DIRECTIONS that plant parts grow in.These directional, or tropic, movements can be either towards the stimulus or away from it.So, in two different kinds of phototropic movement, shoots respond by bending towards light while ROOTS respond by bending away from it. Types of tropic movements-Phototropism- In this plants grow towards or away from the light.Gravitropism- In this plants SHOW some growth in response to gravity. Chemotropism- In this plants grow in response to certain chemicals.Thigmotropism- In these plants move in response to contact with a solid object.Hydrotropism- In this movement of a plant in relation to the stimulus of water.Thermotropism- In this plant responds to the changing atmospheric temperature.Explanation-The movement of plants with the response to a stimulus is called tropic movement.These movements can either towards the stimulus or away from it.Tropic movement is due to cell enlargement.This depends upon the direction of the stimulus.It doesn't affect the whole plant.Thereby tropic movement takes place MAINLY by cell enlargement. There is no growth involved in this tropic movement.On the other HAND, the directional movement of a seedling is caused by growth.If it is prevented from growing, it will not show any movement. Plants respond to stimuli slowly by growing in a particular direction.Because this growth is directional, it appears as if the plant is moving.