1. Plants in Motion
Tropism in plants

2. Background
A stimulus is anything in the environment that causes a response in an organism.
The response often involves movement either toward the stimulus or away from the stimulus.
Plants respond to stimuli such as touch, light, and gravity.
Some responses of a plant to an external stimuli are called tropisms
A tropism is generally termed “positive” if growth is toward the signal and “negative” if it is away from the signal.

3. How Plants respond to stimuli or Tropisms in Plants

4. Geotropism Response in plants to respond to gravity.
The stem/shoots show negative tropism. (Against gravity.)
The roots show Positive (towards gravity.)

5. Importance of Geotropism
provide firm anchorage for roots.
ensure the plant can get adequate supply of water & mineral salts
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6. Phototropism Response to light.
When a plant grows toward light it is called a positive response to light, or positive phototropism

7. Importance of Phototropism
enables leaves to be in a position to receive as much sunlight as possible for photosynthesis
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8. Hydrotropism Response to water.
Example: plants moving to a higher humidity, roots moving to a greater concentration of water.

9. Importance of Hydrotropism
ensures that a plant gets enough water as a raw material for photosynthesis & enough mineral salts to maintain normal growth
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10. Thigmotropism Response to touch.
The stem bends and twists around any object it touches.

11. Importance of Thigmotropism
Gives the plant additional support.
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12. Nastic Movement
Rapid response of rapid movements of plant organs in response to a stimulus
Used as a defense.
Used to trap its prey in carnivorous plants.
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