Hyeong Jun Jo1P, Seung-Hwan Oh2, Gyu Young Ghung3, Chae Sun Na1

1Wild Plant Seed Division, Baekdudaegan National Arboretum, Bonghwa, Korea; 2School of Forest Sciences and Landscape Architecture, Kyungpook National University, Daegu, Korea; 3Department of Forest Science, Gyeongkuk National University, Andong, Korea

In the world, Euphorbiaceae comprises about 330 genera and 6,500 species. It mainly distributed in the tropical and subtropical regions, with some species extending into temperate areas. In Korea, about 20 species are distributed in eight genera. This study examined 17 species distributed in Korea, including the endemic species Euphorbia fauriei and Glochidion chodoense, and the two alien species E. maculata and E. nutans. The classification followed Engler’s system. Seed micromorphological characteristics are usually considered to be unaffected by environmental factors and are known to be particularly important for identifying the genus Euphorbia. Seed micromorphological characteristics were examined using scanning electron microscopy (SEM). Taxonomically important characteristics were identified as seed size, seed shape, caruncle presence and shape, seed ornamentation, seed surface microsculpture, shape of the periclinal wall and anticlinal wall, these characteristics were useful for interspecific identification. In particular, G. chodoense, Flueggea suffruticosa, Phyllanthus urinaria, and P. ussuriensis—taxa formerly treated within Euphorbiaceae—were all observed to have a sectoroid, three-sided seed shape. Accordingly, these four species are better treated within Phyllanthaceae under the APG IV system rather than Euphorbiaceae of Engler’s system.