A review undertaken as a part of a more comprehensive work on the chemical factors of the environment that operate in living organisms. This, first paper of a series, deals with the occurrence, form and structure of aluminum as it exists in the pedosphere and in the hydrosphere, and of its occurrence in plant families of the biosphere. Here the Symplocaceae are perhaps the best aluminum accumulators. In some of these there is as much as 27% Al in the ash, or 2.61% in the dry plant.