The New Student's Reference Work/Thermotropism

Thermotropism (thẽr-mŏt′rō̇-pĭz’m), the sensitiveness of a plant to heat coming from one side, in response to which the rate of growth is so unequally affected as to cause the part to bend toward or away from the source of heat; e. g., corn-seedlings and hyacinth-leaves bend toward a warm iron-plate (30°C) placed near them; cress-seedlings turn away from it. See Growth and Irritability.