Article

The complex 01' plants flowering in mid summcr on the marble slopcs or Pirin MIs. were classified according IO the morphology oftheir " blossoms" (flower or compacI inflorescence) in thc lo ll owing basi e classes: I) "d ish/bow]" - free acccss to the nectar and pollen, 2) "beli" and " rullncl" - more or less hidden nectar, 3) " flag" (sternotribic poll ination) ami 4) "gulle'" (nototribic po llination). The highest numbcr of plant spcc ics have "gullet", "dish!bowl + funneUtube" and "dishlbowl" shaped bloSsoms. Vellow and purple coloms are equaJly presented by highest number of species. Next highest number of plant species have white blossoms. On Pirin marbles "gullet" morp h is usua lly combined w ith purple co lour. The "dish/bowl + funnel/tube" blossoms are usually purple while those shaped as "dishfbowl" are usually ye llow. Also high is the number ofplant species with "flag" blossoms which are usua lly bright or pale yellow. Most abundant are plant spccies with yellow and purple blossoms Iì·om different structural classcs. Bumblebees were thc most frequent bec visitors. All of them showed preference to " flag" and "gullet" blossom morph, mainly purple and yellow. Highest average visitation rate (number ofvisitors per mi nute) showed workers Bombus pratorum. Next most active bumblebees were B. lapidarius and B. mastrucatus.