Anatomical features and stomatal gas exchange of the leaves of Melastoma candidum grown in hilly and swampy habitats were compared． The cells of upper epidermis was thicker with smaller cells which were closely arranged， and the stomatal density being higher in hilly melastoma compared to those in swampy one． Thicker sponge tissues，larger maximum vessel diameter，and higher ratio of palisade cell height to cell width were observed in swampy melastoma．However，the ratio of palisade thickness to sponge thickn ess was lower in swampy melastoma than that in hilly one． There were little diferences in the contents of chlorophyll a and chlorophyll b， carotenoid and chlorophyll a／b between hilly and swampy melastoma．The hilly melastoma had lower net photosynthesis rate，transpiration rate and stomatal conductan ce than those of swampy melastoma．The diurnal courses of average water use eficiency(net photosynthetic rate／transpiration rate，WUE)were similar between plants grown in two habitats．Intrinsic water use eficiency(net photosynthetic rate／stomatal conductance，Intrinsic WUE)was lightly higher in swampy melastoma than that in hilly one，but no significant diference was found． It is proposed that these diferences between two populations of melastoma might be mainly due to the diferent soil conditions． However， the above results could not confirm that the hilly an d swampy melastoma are diferent ecotypes.
