Indicator plants allow to determine the state and stability of phytocenosis. The study of properties of indicator plants is possible with the help of a mathematical model of shoot morphology. Due to the impact of environmental factors, plants change the structure of stem and leaf. The development of a mathematical model of the shoot is carried out by determining the parameters of morphology and architectonics of stem and leaf. For this purpose, the dimensions of morphology elements are investigated and the proportions between them are established. An important characteristic of an indicator plant is the amount of variation in the size or proportion of a morphology element relative to the average. If the variation of parameters of morphology or architectonics element is very large, it cannot be used to indicate the impact of environmental factor on the plant. In case the parameters of morphology or architectonics elements are stable, they can be used for a mathematical model of a shoot. An indicator plant should have at least one stable parameter of morphology or architectonics that changes its value under the influence of an environmental factor.
