The influence of moderate water deficit on both the ultrastructure of epidermal cell walls and cellulose content in the walls of Sium latifolium leaves during flowering and fruitage stage was studied. The ultrastructure of walls of adaxial and abaxial surface was studied by the scanning electron microscopy. Complex of cellulose with calcofluor in the cell walls of both adaxial, abaxial epidermis and mesophyll of two ecological forms of S. latifolium leaves was visualized by the laser-confocal microscopy. S. latifolium plants grew in water and under influence of moderate water deficit. The images of quantitative distribution of cellulose in the cell walls were obtained on cellular level depending on the type of leaf tissue, growth stage and on the conditions of plant growth. The decrease of amorphous cellulose and the increase of crystalline cellulose were established in the process of growth and under the influence of water deficit. The role of cellulose in the cellular mechanisms of adaptation to water deficit is discussed.