The answer for the question is hydrotropism. Tropism is the directional growth of an organism, typically a plant, in response to an external stimulus, such as light or gravity. Growth towards the stimulus is called the positive tropism, while the growth away from the stimulus is referred to as negative tropism. In this case; hydrotropism is a type of tropism where plants bend their roots towards the source of stimuli, that is water or moisture. The importance of this tropism is to seek more water for use by the plants.