AbstractsBiology & Animal Science

Because of their poikilothermic and hydrated nature all plants freeze when exposed to temperatures below the freezing point of water. That intemperate regions trees and exposed parts of shrubs and herbs are frozen solid for some time during the cold season and that the vast majoritysurvive this treatment regardless of the extremes of low temperature reached with slight if any injury, is a matter of common observation. Butthe slightest exposure of the plant to a few degrees of frost in the warm season, providing it is sufficient to cause freezing, is fatal.Death in this case is the direct result of the formation of ice as evidenced by the fact that a plant can be supercooled far below the freezingpoint of its tissues without injury; prevention of supercooling by stimulus to crystallization will result in the immediate death of the plant andthis at a temperature which if it is not at the freezing point of its tissues is well above that reached by supercooling without injury. [...]