Abstract: This paper deals with the structure, development and composition of the lithocysts and their cystoliths in the epidermis of leaf in Broussonetia papyrifera (L.) Vent. Both epidermal layers had the hair-like lithocysts. The lithocyst seen in the adaxial epidermis had a central hair-like lithocyst with 1–3 rosette-forming small round lithocysts at its base which was absent in the comparatively fine hairy litbocyst on the abaxial epidermis. All these lithocysts had cystoliths. The hair4ike lithocysts in adaxial epidermis developed more quickly, and showed obvious“gliding growth”. One or two stalks were seen clearly in the early stage of the cystolith development. Later, the stalks were covered gradually by the cystolith deposition. The majority of cystoliths were mainly composed of polysaccharides, also mixed with a little suberin and calcium carbonate. But, large variation in material composition was found in different cystoliths and different developmental stages of individual cystolith. Exceptionally, there were large amorphous and shaped crystals of calcium carbonate in the cystoliths of the hair-like lithocysts. The ultrastructure of cystolith components exhibited no orderly arrangement and there was no stratification as seen under optical micoscope.

Key words: Broussonetia papyrifera, Lithocyst, Cystolith