Internal Suberization of Tissues

Abstract

The general term suberin here connotes a translucent wall material resistant to strong chromic acids. The internal surface (intercellular space) in leaf, stem, root, flower and fruit is lined by a suberin lamella. The inner surface of all cell walls examined is also lined by a tenuous film of apparently similar material. The degree of internal suberization varies in hydrophytes, mesophytes and xerophytes, and in younger and older tissues. Suberin may impregnate the entire cell wall in old hard leaves so that, after treatment with H2SO4 (80%), the cell outlines remain unchanged. The aging of cells is accompanied by progressive suberization and intensification of fat metabolism. The inner surface of vessel segments and of other cells may be micropitted and the surface of the protoplast correspondingly micropapillate. Microplasmodesmata may extend from these micropapillae into the cell wall. The significance of internal suberization must be considered in the future discussion of solute transport, transpiration, respiration, fat metabolism, and permeability.