Pollen and Capsule Morphological Studies on Verbascum Hybrids (Scrophulariaceae) in Mardin, Turkey and Their Taxonomic Importance

Abstract

Verbascum (Scrophulariaceae, Lamiales), usually known as “Mullein”, is widely distributed in Eurasia and North Africa, but the highest taxa diversity is in Anatolia, the southern Balkans, the Middle East, the Caucasus and northwestern Iran and is represented by approximately 360 species in the World. As hybridization is very dense in the genus Vesbascum, the high frequency of morphological variations has been intricated in species delimitation. In this study, pollen and capsule morphology of three hybrid Verbascum taxa [Verbascum x calcicolum Hub.-Mor., V. x kotschyoides Hub.-Mor., and V. x nusaybinense Hub.- Mor.] were investigated. They are hybrids wild distributed in the province of Mardin in Southeastern Anatolia. Pollen slides were prepared according to the Woodhouse method, pollen and seed morphologies were examined with microscope. In general terms, aperture types were tricolporate, but also tricolpate aperture types were observed. The shapes of the pollen grains were determined as oblate-spheroidal and subprolate. The sculpture was reticulate in all cases. The seeds not developed. The capsules are pubescent, densely covered by branched hairs, or loosely by glandular hairs, depending on species. The results of this study showed that morphological features, such as pollen shape, polar axis length (P), equatorial diameter (E), aperture type, exine and intine thickness, colpus, and por measurement, show differences that can be taken into consideration in the systematic discrimination within the taxa. The capsule showed that substantial taxonomic insight can be gained from examining the capsule characteristics of Verbascum, particularly at the species level.