Abstract
To clarify the relationship between the occurrence of aquatic macrophytes and the chemical nature of the water, the flora of aquatic macrophytes grown in 122 irrigation reservoirs in Tokai District was investigated along with some major elements (pH and concentrations of Ca, K and Mg) in the water of 65 randomly selected reservoirs. By dividing the irrigation reservoirs into three altitudinal locations (plain, lower hillside and higher hillside), it was revealed that 23 species of the aquatic macrophytes (exclusive of two omnipresent species, Phragmites communis and Zizania latifolia) inhabiting these reservoirs could be classified into six groups.
Since both pH and the concentrations of the three elements in the water gradually lowered with the higher altitude of reservoirs, it was supposed that the flora of each reservoir was considerably influenced by some elements of its water, and the latter must in turn have been affected by the geographical feature of the basin in which the reservoirs were located.
