Flower morphophysiology of selected Lamiaceae species in relation to pollinator attraction

Abstract

The floral biology and attractiveness of five Lamiaceae species, namely Hyssopus officinalis, Lavandula officinalis, Melissa officinalis, Salvia officinalis and Salvia sclarea, were studied by correlating morphological characteristics of flower and nectar production with pollinator visits, especially with reference to honey bee forage preferences. Although these species are cultivated for medicinal purposes, they also represent a significant source of pollen and nectar for honey production, so the investigation aimed to estimate their melliferousness and significance for bee pasture. Pollinator observation indicated the visitation of seven species of Hymenoptera, three species of Diptera and two species of day flying Lepidoptera. The honey bee (Apis mellifera) was the most abundant pollinator, and the major elements of attractiveness were flower scent and colour, followed by the shape and size of the corolla and to a lesser extent nectar abundance. Corolla tube length and number of open flowers per whorl were of little significance. According to all analyzed flower characteristics and observation of pollinator behaviour and visits, the most attractive plants were H. officinalis, S. officinalis and L. officinalis, whilst M. officinalis was the least attractive and S. sclarea completely unattractive to all recorded pollinators except for Xylocopa violacea.