Abstract
This paper reports new stands of subatlantic Spergulo-Chrysanthemetium segeti associalion, found on the Olsztyn Lake District area. This association is very seldom described from Poland. It occurs in spring crops and root crops cultivations. The most important attributes of this association are: a mass occurrence of Chrysanthemum segetum, a numerous occurrence of Spergula arvensis, a big contribution of Centauretalia cyani species and habitat's humidity, indicated in the presence of numerous hygrophytes. Communities of this assciation found on Olsztyn Lake District are similaI to the other Spergulo-Chrysanthemetum segeti phytocoenoses, described from the other regions of Poland. However, they show a little differences too. The most important of them are: very small paIticipation of Eu-Polygono-Chenopodion species and the absence of Panico-Semrion species, general floristic scantiness and small participation of Chrysanthemum segetum and Spergula arvensis in the most of records. Spergulo-Chrysanthemetum segeti communities occur very seldom in the central part of the Olsztyn Lake District and they are probably the farthest advanced to the east, known stands of this association in Poland.