Adaptation to Desiccation

Abstract

Desiccation tolerance is a feature of plants capable of experiencing protoplasmic dehydration without permanent injury. Except for the seed stage, this latter mechanism is poorly developed in the majority of higher plants. Losses greater than 40–90% of normal water content (Levitt 1972), or equilibration with relative humidities lower than 91–98% (Levitt et al. 1960) are lethal for most higher plants. By contrast, many lower plants (and some angiosperms) are remarkable in the ability of their vegetative tissues to withstand extreme drought and desiccation. Known also as poikilohydrous plants (Walter 1955b), poikiloxerophytes (Henckel and Pronina 1968), or resurrection plants, these desiccation-tolerant plants are loosely defined by their unique ability to revive from an air-dry condition (the air having a low relative humidity). Plants that succumb to desiccation are called desiccation-sensitive, desiccation-intolerant or homoiohydrous plants (Walter 1955b).