The distribution of cellulose in the cells of epidermis and mesophyll of Sium latifolium leaves at the phases of flowering and seedling by the laser-confocal microscopic method has been investigated. The dependence of the relative content of cellulose in cell walls on the tissue type, phase of plant ontogenesis and the environment conditions has been established by using of PASCAL Program. It has been revealed that moderate water deficit leads to decrease of amorphous cellulose content and to increase of crystalline cellulose content during plant growth.