noun, plural: photoropisms
Tropism is an orienting response of an organism to a stimulus. Thermotropism is one of the many forms of tropisms. It pertains to the movement or the growth response of an organism to heat or changes in temperature. The response may be positive or negative. A positive thermotropism is when the growth or movement of an organism is towards the source of heat. A negative thermotropism is when the organism tends to grow or move away from the source of heat. An example of thermotropism is the curling of Rhododendron leaves during cold temperatures. Another instance of thermotropism is the collapsing of leaf petioles leading to the folding of leaflets of Mimosa pudica also during cold temperatures.1
Thermotropism should not be confused with thermotaxis. Thermotaxis is manifested by the directional movement of an organism in response to temperature. Thermotaxis involves the movement of the entire organism and not just a part of an organism just as it is in thermotropism.
Word origin: Ancient Greek thermós (“warm, hot”)+ tropism
- thermotropic movement
1 Thermotropism. Retrieved from .