Petal epidermal micromorphology of Korean Peucedanum L. species (Apiaceae) and its systematic significance

Peucedanum L. (Apiaceae) is broadly distributed in the Old World, and 11 taxa, including five endemic species, have been reported in Korea. In this study, we used scanning electron microscopy to describe petal epidermal cell patterns and evaluated their systematic implications for all Korean Peucedanum species except for one. This included two recently reported endemic species, P. miroense and P. tongkangense, which are closely associated with Heracleum moellendorffii. The epidermal characteristics of the petals, including cell type (papillose conical, papillose knobby rugose, tabular conical, or tabular rugose), anticlinal wall shape (straight, sinuous, or curved), cuticle sculpture (striate or wrinkled), and stomata (presence or absence) were observed. The petal epidermis could be categorized into three types and two subtypes. We concluded that petal epidermal characteristics provide evidence supporting the recent robust phylogeny that suggests the non-monophyly of the genus Peucedanum. In particular, P. japonicum and P. praeruptorum, which are positioned in different clades to the other species in the recent phylogeny, had different types of petal epidermis among the studied species. These petal epidermal micro-characteristics were evaluated as possible consistent parameters for the taxonomic delimitation of species of the genus Peucedanum.