A. POLJAKOFF-MAYBER and J. GALE The response of plants to saline environments is of interest to people of many disciplines. In agriculture the problem of salinity becomes more severe every year as the non-saline soils and the non-saline waters become more intensively and more extensively exploited. Further expansion of agriculture must consider the cultivation of saline soils and the use of water with a relatively high content of soluble, salts. Moreover, industrial development in many countries is causing severe water pollution, especially of rivers, and mismanagement in agriculture often induces secondary salinization of soils and sources of irrigation water. From the point of view of agriculture it is, therefore, of the utmost importance to know the various responses of plants to salinity and to understand the nature of the damage caused by salinity to agricultural crops. Botanists and plant physiologists study plants, their form, growth, metabolism and response to external stimuli. A challenging problem for them is to understand the differences between glycophytes, plants growing in a non-saline environment and halophytes, plants which normally grow in salt marshes, in sea water or in saline soils. This includes the elucidation of structural and functional adaptations which enable halophytes to tolerate the saline environment, and also questions as to whether they only tolerate the saline environment or actually thrive in it. Ecologists and environmentalists are interested in the interrelationships be­ tween the organism, in this case the plant, and its environment, from the climatic, edaphic and biotic points of view.