The objects of the investigation are the natural populations of Gentiana lutea and G. punctata, which are not numerous and are highly antropogenic influenced on the territory of Bulgaria. The both species are included in the Red Data Book of Bulgaria and are protected by the low.

A full characterization of the two species` habitats is made - it includes their exact location, altitude, exposition, slope and type of their base rock and soil. The cover of each species is searched, as well the total cover of the whole community. The detailed information about the floristic composition of the phytocenoses is given, as well the quantity participation of accompanied species. The age structure of the population of G. lutea and G. punctata is determined.

The floristic similarity coefficient for each couple phytocenoses for the both species is estimated. The similar communities (with floristic similarity over 40%) are classified in different sintaxonamic categories. Different type of phytocenoses includes G. lutea as a member. Such phytocenoses can be part of the natural or the secondary vegetation. It is more typical for this species to participate in the secondary communities. Such communities are joined in the association Campanulo - Juniperetum sibiricae.

The plant communities of G. punctata belong to the following associations: Ass. Campanulo -Juniperetum sibiricae, Ass. Lerchenfeldio - Pinetum mugo, and Subass. Festuctum pictae achilleetosum clusianae. The populations of G. punctata are more numerous and with higher density than those of G. lutea.