Scanning electron microscope (SEM) and light microscope (LM) studies on the seed morphology of Verbascum taxa (Scrophulariaceae) and their systematic implications

Verbascum L. is the largest genus of the family Scrophulariceae and includes several species are of medicinal importance. In this study, external seed morphologies of 30 taxa included in Group A belonging to genus Verbascum L. (Scrophulariaceae) in Turkey, have been investigated using SEM (Scanning Electron Microscopy) and LM (Light Microscopy). Light microscope observations showed that seed size ranges from 0.3 mm to 1.5 mm in length and 0.1 to 0.6 in width. Seeds vary from oblong, oblong prismatic, trigonious prismatic, prismatic, ovoid to eliptic in shape among the studied species. The seeds end to an acute, obtuse, truncate or rounded beak. The seed coat is transversal ridged or alveolate. The results of this study showed that considerable taxonomic insight can be gained from study of seed characters of Verbascum, especially at the species level. The variation in seed morphology is manifested mainly in shape, size, colour, seed coat ornamentation. To make a conclusion about the delimitation under the genus Verbascum based on the seed characteristics, all taxa included in the genus should be studied comparatively.