Cytological studies of 14 Chinese species ofParnassiaL. (Par-nassiaceae) and its phylogenetic implications

Abstract

The chromosome numbers and karyomorphology of 14 Chinese species of the genus Parnassia were in- vestigated. The chromosome numbers of 11 species were reported for the first time. The report of 2n=48 for P. monochrofolia Franch was new to the Chinese species of the genus. There are about 30 species cytologically studied up to now. From the available data, the species of Parnassia with the basic chromosome numbers of x=7, 8 and 9 were found in China and the Himalayas, in which the more species with x=9, as well as mainly in western N America, while x=8 was only found in eastern N. America. Polyploidization was common in the genus, more extensively in Northern America. Based on our results and the previously reported data, the basic chromosome numbers and poly- ploidization are discussed. Combined with gross morphology and geographical distribution of Parnassia, the phylo- genetic implications of the cytological data are also discussed. It is suggested that eastern Asia and western N America are probably the modern divergent centers of the genus.