Tropisms

The manner in which plants react to their surroundings is known as tropism. There are a number of different tropisms associated with certain plant types and the stimulus required varies greatly.

Observations of cress seed growth toward light source. This form of tropism is known as phototropism and occurs in all plants.

Observations of thigmotropism (reaction to touch). This tropism is mainly found in climbing plants. Although all plants have a thigmotropic reaction in their root systems this used to avoid objects while growing rather than to grow around objects as with climbing plants.



Cybernetic diagram for thigmotropism.