Rumex kerneri Borbás (Polygonaceae) in the Bulgarian flora – Morphology, Leaf Epidermis, Pollen Morphology, and Karyology

The current study provides detailed information about Rumex kerneri Borbás in the flora of Bulgaria. The data about this species in the floristic literature is contradictory and uncompleted. The morphologically closely allied species R. cristatus DC. и R. patientia L. misleads in the determination of the species. Both species are used as a referent to establish the discrete morphological characters and metrics. The current study provides detailed information about pollen and fruit morphology, leaf epidermis, and karyology of Rumex kerneri Borbás in the flora of Bulgaria. The data about this species in the floristic literature is contradictory and uncompleted. The most reliable characters in the differentiation between R. cristatus are R. patientia the reduced number of flowers in a cluster of R. kerneri, the development of only one tubercle in the mature valves, and the abaxial surface of the leaf blade. Also, the pollen morphology (light and scanning electron microscopy) was confirmed in this study. The somatic chromosome number of the species 2n = 80 is also given. This is the first chromosome number for the taxon from Bulgaria and confirms the earlier reports.