Animals move in search of food, shelter and for reproduction. Plants do not move on their own from one place to another, but they can move their body parts for getting sunlight, water and nutrients. They are sensitive to external factors like light, gravity and temperature. This chapter covers the movements in plants (tropic and nastic), photosynthesis and transpiration.
1. Movements in Plants – Introduction
- The leaves of Mimosa pudica (touch-me-not plant) close on touching.
- Helianthus annuus (sunflower) follows the path of the sun from dawn to dusk (from east to west).
- These movements are triggered by an external stimuli.
Plant movements are of two kinds: tropic movements and nastic movements.
2. Tropism in Plants
Tropism is a unidirectional movement of a whole or part of a plant towards the direction of stimuli. In other words, it is a growth movement whose direction is determined by the direction of the stimulus.