The herbaceous vegetation is very diverse due to the favourable climate and soil conditions, as well as the limestone bedrock. The Bulgarian section of Slavyanka is the only habitat of the endemic Convolvulus suendermanii. Important protected species include the black maidenhair fern (Adiantum capillus-veneris), Polygala nicaeensis, Rhamnus fallax, as well as the Balkan endemic species Fritillaria drenovskii, restricted to Slavyanka, Pirin and northern Greece, Pulsatilla rhodopaea, Saxifraga siribrnyi, long-spur violet (Viola delphinantha), restricted to this area of Bulgaria, as well as Greece, Paril centaurea (Centaurea parilica), restricted to Slavyanka and southern Pirin, etc.