Flowering biology and pollen production of four species of the genus Rosa L.

Abstract

Wild growing rose species are of great importance as a source of pollen for insects. Oil extracted from the petals of various <em>Rosa</em> species is used in perfumery, cosmetic industry, and therapeutics. In our study, we compared the flowering duration and flower lifespan, the number of stamens and pistils, the mass and size of pollen grains as well as the anatomical features of the petals of four <em>Rosa</em> species: <em>R. canina</em>, <em>R. ×damascena</em>, <em>R. gallica</em>, and <em>R. rugosa</em>. Moreover, we examined the pollen loads collected by bumblebees foraging on rose flowers in order to determine the attractiveness of pollen of this genus to insects. We showed the flower lifespan to vary (3.5–8 days) in the roses studied and revealed high variation in the number of stamens (82–260) and pistils (17–65) as well as in the mass of pollen produced. The flowers of <em>R. rugosa</em> produced the highest amount of pollen (26.7 mg per flower), while the flowers of <em>R. canina</em> the least (3.3 mg per flower), which is associated with differences in the number of stamens developed in the flowers between these species. The largest pollen grains were found in <em>R. </em>×<em>damascena</em> and <em>R. gallica</em>. We demonstrated that <em>R. ×damascena</em> produces the thickest petals and that scent-emitting papillae found on the adaxial surface of the petals differ in size and shape in the rose species investigated.