Morphological and chromosomal variation in Fallopia section Reynoutria (Polygonaceae) in Korea

We have examined morphological and chromosomal variation in Fallopia sect. Reynoutria in Korea to clarify their taxonomic identities and to determine whether their morphological variability is associated with ploidy levels. P rincipal components analysis (PCA) of individuals from 21 populations, usin g major distinguishing characters, revealed the presence of four major enti ties of sect. Reynoutria in Korea; these include F. sachalinensis, F. japon ica var, japonica, F. forbesii, and the Nonsan population consisting of pre sumed hybrids. Based on morphology, it is hypothesized that the Nonsan popu lation was probably derived from multiple hybridization events involving th e three: named taxa. The results also indicate that F. forbesii is distinct from F. japonica var, japonica. Polyploidy is more prevalent in sect. Reyn outria than has been previously recognized. Fallopia sachalinensis in Korea occurs as dodecaploids with 2n = 132; our count is the first dodecaploid c ount for the species, and represents the highest chromosome number known in the genus. Fallopia japonica var, japonica occurs as tetraploids (2n = 44) , hexaploids (2n = 66), and octoploids (2n = 88), while F. forbesii occurs as hexaploids (2n = 66) and octoploids (2n = 88); our counts appear to be t he first reported chromosome numbers for F. forbesii. Morphological analysi s indicates that there is no apparent correlation between the ploidy levels in these taxa and the morphological characters that we have considered in this study except that the tetraploids of F. japonica var. japonica tend to have somewhat thicker leaves.