The purpose of this study is to elucidate the characteristics of Brasenia purpurea wild growing reservoirs(Keum Ho and Cheok Po Jae) by comparing the limnological condition with other reservoir(Kim Si Jae) which has no wild growing of this plant of Chun Nam Province during Spring, Summer, and Autumn in 1977. The results obtained are as follows 1. B. purpurea wild growing reservoirs. Cotaining small reservoirs in Keum Ho Jae catchment and the greater part of the woody land in Cheok Po Jae catchment all diminish the earth carrying into the reservoirs and keep up the bottom of the basin structure formed spontaneously by earth dam erosin for long time. On account of the bottom basin a little water are left after maximum drainage and aquatic plants are protected from drying up. Therefore thick nutrious sediment layer are formed in the bottom by plant deposit. Low water depth at all times, making latent capacity in store large in flood and flushing rate small, diminish the loss of nutrients from the reservoirs. Above all condition with the comparatively large loading rate of nutrients make the reservoirs high eutrophication. The high concentration of P, K, N, Mg, Ca, optimum temperature, and high transparence elevate highly the photosynthetic faculty of plant. The highly saturated DO elevate the oxidative autopurification faculty and accelerate the inorganization of organic substance and accumulate a lot of nutrients in the reservoirs by increasing the precipitation of the insoluble phosphate and suppressing the denitrification in the bottom water layer. The high concentration of the total salt seem to prevent dissolving the gel which cover the young leaf of B. purpurea. Therefore B. purpurea wild growing reservoirs are very likely to have symmetrical environment and fit for the aquatic plant. 2. B. purpurea non-growing reservoir On account of the major part of the bare land in the catchment the large amount of the earth are carried into the reservoir in flood, having neither basin structure nor sediment in the bottom. Small latent capacity in store make flushing rate large in flood and the big drainage rate make the loss of nutrients large. Above all condition with the comparatively little loading rate of nutrients result the reservoir in poor nutrient accumulation. The low concentration of nutrient salt, deep water, and high turbidity make unfit environment for aquatic plant growing, especially for B. purpurea.