XVI International Botanical Congess

Filamentous green alga Cladophora aegagropila is well known developing into spherical aggregation, and it has been preserved as a special natural monument in Japan. To explain relationship between polymorphous life mode and environmental structure, the data obtained from Japanese 15 lakes was analyzed. The life mode was classified in 3 types, and appearance of the each in the field correlated closely with grade of substratum (Gs), depth (D) and attenuation coefficient (Ac). D and Ac are parameters for photosynthesis, and Gs and D are intimately related with flow and distribution of the alga due to water current. A model for illustrating the polymorphism was constructed based on the flow and the production.