Flower micromorphology of eight wild-growing Rosa species ( Rosaceae ) from Serbia

In the present study, the surface and external structure of petals, sepals, hypanthium and pedicel of eight Rosa species were examined. Micromorphological investigation of distribution and dimension of different trichome types, which were found in analysed plant parts was done using scanning electron microscopy (SEM). Our results showed that the adaxial epidermal cells of all analysed petals formed papillae, whereas the abaxial epidermis was with flat walls and had cuticle striation. Two types of trichomes, the capitate glandular and nonglandular trichomes (ribbon and acicles) were observed. Ribbon trichomes were presented on the adaxial side of all analysed sepals with the exception of R. spinosissima samples. Multicellular glandular trichomes were distributed on the surface of the hypanthium and the sepals of R. gallica , R. micrantha , R. pendulina , R. tomentosa and R. villosa samples. In addition, they were presented on the pedicel of most analysed species, except in R. dumetorum samples. Micromorphological analysis had shown that capitate glandular trichomes, based on their size, can be classified into two typeslong and short trichomes. Their presence, type and length were specific for each analysed species. Additionally, acicles were found only on the pedicel and hypanthium of R. spinosissima and R. gallica samples. This study provided useful information of different trichomes of genus Rosa which could be helpful in more accurate plant determination.