Gyu Young Chung

Chromosome numbers of 28 taxa in 10 genera of the Ranunculaceae (buttercup family) from the Korean peninsula

Somatic chromosome numbers of 28 Korean native species in the buttercup family are observed and analyzed. The plants include 10 genera with seven endemic taxa to the Korean peninsula, and most of them are the first reports from Korean populations. In particular, the chromosome numbers for the two taxa are reported for the first time: Clematis fusca var. coreana (H. Lév) Nakai (2n = 16) and Thalictrum aquilegiifolium var. sibiricum Regel & Tiling (2n = 42). The Ranunculus type chromosomes (R-type, c.3–12 μm long) are found in Megaleranthis, Actaea, Cimicifuga, Anemone, Clematis, Hepatica, and Ranunculus, whereas Aquilegia and Ranunculus have the Thalictrum type chromosomes (T-type, c.1–1.5 μm long). The two types of chromosomes in Ranunculus, one of the species-rich genera in the family (c.600 species worldwide), suggest that chromosomal differentiation plays an important role in species diversification in the genus. Evaluation of cytogenetic features in a phylogenetic frame is suggested for a better understanding of the evolutionary history of the family.

Relationships of Korean Euphorbia L. ( Euphorbiaceae ) based on pollen morphology

Pollen morphology of 13 species of Korean Euphorbia was re-examined by means of LM and SEM. Taxonomic evaluation of palynological characters and relationships among taxa were also discussed based on the analysis of polar length, equatorial diameter, aperture size and exine thickness. Korean Euphorbia species were classified into three groups based on the mean size of polar length (P) and equatorial diameter (E) as follows:Group 1. sect. Tulocarpa and Tithymalus of subgenus Esula; , Group 2. sect. Esula and Helioscpiae of subgenus Esula; , Group 3. sect. Chamaesyce and Hypericifoliae of subgenus Chamaesyce; . Various features of surface sculpturing were also grouped into 8 types by the characteristics of perporation size and distance of perporations as well as connection state of it. Pollen size and surface sculpturing were comparatively available in the levels of subgenus and section. Especially subgenus Chamaesyce was distinctly different from subgenus Esula by having compactly distributed perporations on exine surface as well as its small size of pollen grains. Because of the great variations in pollen size and the occurrence of various types of surface sculpturing according to the local poulations of each species, it was evaluated that they were unsuitable in classifying each species of Euphorbia. But such cases, that is, E. hylonoma being more familiar with E. ebracteolata than E. Pallasii, and E. pekinensis and E. fauriei as well as E. pallasii being strongly related with each other based on the similarity of surface sculpturing, reflected its usefulness in the classification of some Euphorbia species.