Anatomical and ultra-structural investigations on the vegetative and reproductive characters include stem, leaf, ovary, sepal, corolla, stigma, and seed surface on 10 taxa of the Korean Gentiana (Gentianaceae) were carried out to clarify the section and species limitation, As the results, taxonomic boundaries of the section, subsection, and series were recognized by using characters such as stem, leaf, sepal, ovary, and corolla. Also the seed morphology and testa surfaces were well defined at the species level.