Anatomy of salt excretory structures in certain halophytes in Egypt with a special reference to their re- naming and classification

Abstract

The anatomy of salt excretory structures was studied in 22 dicotyledonous and monocotyledonous halophytic species; 13 of which were not previously investigated. The material was selected to represent obligate and facultative, and succulent and non- succulent halophytes. Structural variations led to their re- naming and classification. For more precise naming it was believed that one should differentiate between ‘glands’ that have no ontogenic relation to the epidermis and the epidermal appendages, and convinced by this, the excretory structures were classified into three types and two sub-types. It was also concluded that the presence of such structures in facultative halophytes, where the concerned stress factor (salinity) is absent, makes it a hereditary character resulting in an adaptive capacity for salt tolerance. Ectodesmata were recorded in the outer periclinal walls of the epidermal cells in some species and were considered to be another mechanism for salt excretion.