We endeavor to enlarge the knowledge about Bulgarian vegetation diversity. Data on seminatural grasslands containing 344 relevés, collected in Southeast Bulgaria were analyzed by the combine method, using TWINSPAN and the Cocktail method. The Erysimo diffusii-Trifolietum angustifolii association and the alliance Trifolion cherleri were established for the first time in Bulgaria. So far the presence of this association was known for Macedonia. The aims of our study are to present more data about the Erysimo-Trifolietum in Bulgaria and to make some comments about its affiliation to Helianthemetea guttati. The association is characterized ecologically and floristically. Analysis of the floristic elements shows that the most numerous are sub-Mediterranean species. Analysis of the life forms shows that these communities are hemicryptophyte-therophytic. A review of syntaxonomical systems and association assignment to higher syntaxa were made. According to current European vegetation surveys the association should be related to class Helianthemetea guttati. Our results reveal an intermediate character of the studied vegetation – closed dry grasslands, with distinct presence of Festuco-Brometea species with a high percent of therophytes and Mediterranean floristic elements related to Helianthemetea guttati as well.Članek je prispevek k poznavanju raznovrstnosti vegetacije Bolgarije. Podatke, ki obsegajo 344 popisov, narejenih v jugovzhodni Bolgariji, smo analizirali s kombinacijo metod TWINSPAN in Cocktail. Asociacija Erysimo diffusii-Trifolietum angustifolii in zveza Trifolion cherleri sta prvič omenjeni v vegetaciji Bolgarije. Do sedaj je bila prisotnost te asociacije poznana le v Makedoniji. Namen raziskave je predstaviti dodatne podatke o asociaciji Erysimo-Trifolietum v Bolgariji in podati nekaj komentarjev o njeni uvrstitvi v razred Helianthemetea guttati. Asociacija je označena ekološko in floristično. Analiza flornih elementov je pokazala, da so submediteranske vrste najštevilnejše. Analiza življenjskih oblik pa, da je to hemikriptofitsko-terofitska združba. Opravljen je pregled sinataksonomskega sistema in uvrstitev v višje sintaksone. Po trenutnem pregledu evropske vegetacije jo uvrščamo v razred Helianthemetea guttati. Naši rezultati pa razkrivajo vmesni značaj obravnavane vegetacije – sorodnost s suhimi travniki s prisotnostjo vrst Festuco-Brometea in visokim odstotkom terofitov in z razredom Helianthemetea guttati, ki ga označujejo mediteranski elementi
