In order to determine the reasons of necrosis of exotic plants leaves cultivated in greenhouses plants belonging to ten following species were examined: Ceratozamia mexicana Brongn., Stangeria eriopus (Kunze) Nash ( Cycadaceae ), Eriobotrya japonica Lindl. ( Rosaceae ), Camellia japonica L. ( Theaceae ), Phoenix roebeleni O'Brien ( Palmae ), Sequoia sempervirens Endl. ( Taxodiaceae ), Calathea bachemiana Morr. ( Marantaceae ), Cordyline terminalis Kunth ( Agavaceae ), Spathiphyllum wallisii Reg. and Anthurium magnificum Lind. ( Araceae ). Chemical analysis were performed in soil samples in which these plants grow, in samples of tap-water applied for watering and in samples of decaying and healthy leaves. In order to examine the process of withdrawal of mineral components from necrotic leaves, both: necrotic and green parts of decaying leaves were subjected to examination. On the basis of the research it was concluded, that - in spite of generally low level of salinity of the water used for watering - some ions content, particularity that of CI - , was unfavourable to plants. Unfavourable ionic composition was discovered in water extracts derived from some of the breeding-ground soils. A comparison of healthy and decaying, necrotic leaves chemism proves that CI - assimilated by the plants from the breeding-grounds and accumulated in leaves, affects them toxically.
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