Floral micromorphological, palynological, and carpological characteristics of the rare endemic Korean species Peucedanum miroense (Apiaceae).

Peucedanum miroense K. Kim, H.-J. Suh & J.-H. Song, recently reported as a new species endemic to South Korea, is distributed on mountains Duta-san and Swinŭm-san in Gangwon Province, South Korea. Given its conspicuously limited habitat range and small populations, this species qualifies as an endangered Red List species. In this study, we undertook a detailed investigation of the floral micromorphological, palynological, and carpological characters of P. miroense based on a range of microscopic analyses. Examination of the floral micromorphology of P. miroense revealed that the surface patterns of bractlets have potential utility in taxonomy studies of the genus Peucedanum. In addition, we established that this plant is characterized a papillose conical-tabular rugose pattern of petal epidermal cells and bears sunken nectary slits on the stylopodium. Also identified were simple spherical orbicules bearing psilate surface ornamentation, as well as small tricolporate prolate to perprolate pollen grains characterized by verrucate and gemmate ornamentation. Moreover, we verified pollen wall stratification and presence of pollenkitt. The mericarps had colliculate-striate surface patterns with trichomes and eight or nine vittae, and prismatic crystals were detected in different layers of the pericarp. We believe that the findings of this study will contribute to an evaluation of the taxonomic significance of this species within the genus Peucedanum, and also provide valuable information for the conservation of this rare endemic species. RESEARCH HIGHLIGHTS: We provided the first detailed descriptions of the floral micromorphological, palynological, and carpological characters of the rare endemic Korean species Peucedanum miroense K. Kim, H.-J. Suh & J.-H. Song, based on different microscopic analyses. Our findings provide valuable information regarding the epidermal cell patterns of bractlets, petals, stylopodium, gynoecium, and anthers. We believe our study makes a significant contribution to the literature, as our findings will contribute to enhancing the taxonomical classification of species within the genus Peucedanum, and will provide a basis for the conservation of this rare endemic species. This results will be of value to researchers studying the future biology and taxonomy of species within the family Apiaceae, particularly those using different microscopic techniques, including FE-SEM, digital slide scanning, and TEM.