The carnitine content of etiolated barley leaves doubled on exposure to light. After 24 hr exposure the carnitine content was the same as that of barley leaves grown in 18 hr days; Phosphatidylethanolamine could not be detected in the leaves of less drought-tolerant varieties of wheat (S-308) and barley (BG-25) when the plants were subjected to water stress at tillering, ear emergence and grain filling stages. However, it remained unchanged in the more drought-tolerant varieties C-306 (wheat) and C-138 (barley). Upon release of stress by subsequent irrigation phosphatidylethanolamine reappeared in less drought-tolerant varieties