The ecology of the freshwater phytoplankton — communities of freely-dispersed, plant-functioning microbes — has attracted attention in Britain for over 100 years. Here an outline history is given, with reference to persons and places, types of water-body involved, and the approaches adopted. The last include taxonomic resolution and composition with range of morphotypes; physiology of growth, photosynthesis and nutrition in relation to environmental variables; population sampling, dynamics and controlling factors; experimental mesocosms; and synecological aspects of communities. Reductionist and autecological approaches have been accompanied by more abstract generalisation, including phytoplankton viewed as a model community.