Chromosome study on woody plants by young leaves and buds - especially on plants belong to Hamamelididae

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Karyomorphology in eighteen families of twenty-four families belong to woody Hamamelididae were investigated in an effort to contribute to an understanding of chromosome evolution and inter- and intrafamilial relationships. In the eighteen families, karyomorphology of seven families : Platanaceae, Hamamelidaceae, Eucommiaceae, Ulmaceace, Rhoipteleaceae, Juglandaceae and Myricaceae, have been reported (or in press). The results showed that karyomorphology at interphase, prophase and metaphase, and chromosome number within the genus of respective family showed similar chromosome features. At metaphase all the genera investigated of woody Hamamelididae, however, have chromosomes with median centromeres, those with submedian centromeres and those with subterminal (or terminal) centromeres at different frequencies, excepting that Myricaseae (Myrica) has chromosomes with median centromeres. The morphology at interphase of most families showed similar features, while the Ulmaceae had two types of interphase nucleus ; the simple chromocenter type and the diffuse-complex chromocenter type. In conclution, the present study suggests that, if available, karyomorphological evidence can properly be incorporated in further refining supergeneric classification within Hamamelididae. A further karyomorphological study on more genere (families) and species is necessary for the purpose.