According to the recent monograph of genus Deparia by Kato (1984), D. petersenii is a species defined by single character of its spcecial serrated indusia. This species is morphologically very variable both in size and leaf shape. However, its variation is completely continuous when we compare the plants from distant localities of its wide distribution ranges form East Asia, Southeast Asia, Oceania and many Pacific Islands. The porpose of this study is to investigate whether these morphological variations are completely due to plasticity or several biological distinct units are contained in D. petersenii. In this study, we collected about 100 plant samples covering its interspecific morphological variation from total of 30 different localities in Japan, Taiwan, China and New Zealand. We planted them in greenhouse of KYO to observe morphological plasticity. We used cytological (chromosome number) and molecular (nucleotide sequence data of rbcL and ndhF genes) information to reveal biological units in D. petersenii. As our result of cytological analysis, we newly found hexaploid (6x) and pentaploid (5x) plants from Japanese materials, whereas only tetraploid (4x) had been recorded from D. petersenii by Kurita (1960, 1967). High correlation between ploidy level and leaf size was observed. The 6x plants were smaller than 4x plants, and the 5x plants were intermediate between them. And these sizes were stable even after plants were transferred to the greenhouse. Based on the molecular analysis, we found 14 haplotypes. Six and five of them were restricted in 4x and 6x, respectively. One of each haplotype was shared between 4x and 5x and between 6x and 5x. The remaining two haplotypes were found only in 5x. Thus, 4x and 6x did not share any haplotypes of plastid DNA and shown to be genetically differentiated. Hybrids (5x) might have prevented us to recognize distinct biological units with in D. petersenii.

Key words: Deparia petersenii, hexaploid, ndhF, pentaploid, rbcL