1.NounThe condition of being poikilohydric; the lack of structural or functional mechanisms to actively regulate the equilibrium between the concentration of water in cell tissue and that in the environment.
"Poikilohydry occurs in such organisms as lichens and bryophytes, which lack mechanisms such as waterproofing cuticles or stomata that can help resist desiccation.; Frequently, poikilohydry is coupled with the capacity to tolerate dehydration or low water content of cell tissue and to recover from it without physiological damage."