Anatomy on leaf cross sections of Begonia from Yunnan,China

The characters of transverse anatomic leaf structures of thirty species of Begonia L.mainly from Yunnan were studied by paraffin method for the first time.The results were as follows:The leaves of studied Begonia species possessed typical characters of shady plant leaves with thin leaves,cross section to be bifacial leaves,differentiation of the palisade tissue and spongy tissue but the palisade tissue to be not flourishing to make up less proportion of the mesophyll tissue.Most epidermis was single.The epidermal hairs composed of multiplayer cells.The stomata were distributed mainly over lower epidermis and stomatic nest was big and the ventilating tissue was utmost flourishing.The keratinous form of epidermal cell was varied(even incrassate,tubercular,lamellar,and so on).The elliptical and spherical chloroplast was distributed mainly over palisade tissue in the mesophyll tissue.The characters of the anatomic leaf constitutions of thirty species showed incomplete unanimity between sections of Begonia but showed complete unanimity among the same stem types in different species;The characters of tissue of leaf cross section were horny layer more thin,less proportion of palisade tissue to mesophlly tissue on the rhizomatous and erect stemmed Begonia,which plants adapted to a weak light and hygrophytic environment,but it was horny layer more thick,big proportion of palisade tissue to mesophlly tissue on the corm Begonia,which plants adapted to a strong light and a little xerophytic environment.