The environment of the oak Quercus robur is precisely classified using a mathematical definition of the environment of a plant previously developed by the senior author. The definition is explained in words and a minimum of symbolism is used. The inclusion of each object in the environment of the oak is justified by a semi‐formalized sentence, fully translated into ordinary English at the first usage. A diagram known as an ‘envirogram’, originally developed for the animal environment, is described. It presents the classification of the environment of a specific organism in simple graphic form. Two envirograms are given, for acorn and mature oak tree. These are the first plant envirograms to be constructed. A simplified community in a small habitat containing oaks and other organisms is described. It is fully analysed using a minimum of symbolism and classified as being of second order. The method gives mathematical precision to the notion that living organisms in a habitat are functionally related and it provides a modus operandi for the analysis of such a community.