Flavonoid chemistry and chromosome numbers of Fallopia section Pleuropterus (Polygonaceae)

Flavonoid chemistry and chromosome numbers of Fallopia sect. Pleuropterus w ere examined to gain insights into the relationships among the taxa within the section. Twenty-seven flavonoid compounds were isolated and identified from taxa of section Pleuropterus; most of them were glycosylated derivativ es of the flavonols kaempferol, quercetin, and myricetin, and of the flavon es apigenin and luteolin. The flavonoid data appear to be useful for taxon delimitation, because all taxa examined are readily distinguished by their flavonoid profiles. In addition, the flavonoid data revealed the presence o f two chemical entities in the section; the first group includes Fallopia m ultiflora (Thunb. ex Murray) Haraldson (with varieties) and Fallopia ciliin ervis (Nakai) Hammer and the second group includes Fallopia baldschuanica ( Regel) Holub and Fallopia koreana Oh & Kim. These groupings suggested by th e flavonoid chemistry are well-corroborated by the chromosome number of the se taxa. Taxa of the first group have chromosome numbers based on x = 11 (2 n = 22, 44), whereas chromosome numbers of the second group are based on x = 10 (2n = 20). Our counts for F. multiflora var. hypoleuca (Nakai ex Ohwi) Yonekura & H. Ohashi (2n = 44), Polygonum multiflorum Thunb. ex Murray (= F. multiflora) var. angulatum S.Y. Liu (2n = 22), F. ciliinervis (2n = 22), and F. koreana (2n = 20) are the first reports for these taxa. Based on th ese results, and in conjunction with morphological evidence, it is strongly suggested that the two groups of section Pleuropterus revealed by this stu dy are not closely allied and may represent separate lineages in the genus Fallopia.