Differences in rehydration of three desiccation-tolerant angiosperm species.

The rehydration characteristics of the desiccation-tolerant plantsCraterostigma wilmsii andMyrothamnus flabellifolia (homoiochlorophyllous) andXerophyta viscosa (poikilochlorophyllous) were studied to determine differences among them. A desiccation-sensitive plant (Pisum sativum) was used as a control. Recovery of water content, quantum efficiency (FV/FM), photosynthetic pigments and chloroplast ultrastructure as well as damage to the plasmamembrane were studied. P. sativum did not recover after desiccation and considerable damage occurred during rehydration. The desiccation-tolerant plants appeared to differ in their responses to dehydration and rehydration. The small herbaceousC. wilmsii generally showed little damage in the dry state and recovered faster than the other tolerant species.M. flabellifolia took longer to recover thanC. wilmsii probably due to the presence of a woody stem in which dehydration-induced xylem embolisms slowed the rate of recovery. The poikilochlorophyllous speciesX. viscosa took the longest to recover because it took longer to reconstitute the chloroplasts and the photosynthetic pigments. Quantum efficiency recovered in all species before water content and chlorophyll content recovered to control levels. The significance of these different responses to desiccation and recovery from desiccation is discussed