Karyotypic differentiation in Allium macrostemon Bunge Karyotype studies on twenty-one populations of eight species in Allium section Rhiziridium Intraspecific differentiation of Pleurospermum hookeri (Apiaceae), and its interspecific relationships with two close relatives in the genus Pleurospermum Isozymes of different geographic populations of Leymus chinensis STUDIES ON THIN-LAYER CHROMATOGRAPHY OF FLAVONIDES FOR DIFFERENT POPULATIONS IN ALLIUM HOOKERI AND ITS RELATIVE SPECIES Intraspecific differentiation of Allium wallichii (Amaryllidaceae) inferred from chloroplast DNA and internal transcribed spacer fragments