Thermotropism

Definition - What does Thermotropism mean?

In plant biology, any type of 'tropism' is a plant's physical response to some sort of external stimuli. The response is typically movement of some sort.

Thermotropism is a form of tropism (movement) whereby the plant displays a growth response or movement according to changes in temperature.

For example, rhododendrons often display physical changes in response to a dip in temperature, and then resort back to their normal state once the weather gets warmer again.

Thermotropism is one of the six main types of tropisms recognized by botanists.

MaximumYield explains Thermotropism

In 1884, the French botanist Philippe Van Tieghem discovered that his plant exhibited faster growth when exposed to optimal growth temperature on one side as opposed to the other side.

While botanists don’t entirely understand the mechanism that triggers thermotropism, several plants have shown a clear physiological response to heating and cooling.

According to research carried out on rhododendron leaves, some leaves might curl in response to the cold in order to protect cell membranes from damage. In fact, botanists noted that wild rhododendron growing in the Appalachian Mountains would regularly display thermotropism and drop in the night due to freezing temperatures, only to straighten up again during the day in response to the morning warmth.

According to botanists, plants also move in the following ways:

  • Hydrotropism (growth or developmental response to water)
  • Phototropism (movement toward light)
  • Gravitropism and geotropism (movement relative to a gravitational field, or toward the center of the Earth)
  • Thigmotropism (plant growth in response to physical contact)
  • Chemotropism (movement in response to a chemical in the environment)
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