In Central Europe Lake Balaton and Kis-Balaton wetland, with its filtering function, are unique natural formations as parts of the Balaton Uplands National Park. The large and coherent water habitat has unique significance in Europe. Natural reeds can be found in Lake Balaton and Kis-Balaton wetland and they provide habitat and food for herbivore organisms, they are valuable factors of nature, water and environmental protection. In our research we visited our measurement venues on a weekly basis and examined the plants. We measured their height above water and the maximum width and length of their leaves. We watched the changes of the water level and the weather conditions during the vegetation period of the reed. We examined common reed in different microclimatic factors during these comparative, phenological examinations we observed differences in the height and leaf area index (LAI).