Cytogenetical studies on the speciation and geographical distribution of some higher plants correlating between Japan and China, with special reference to asteraceae.

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The following plant-groups from China were studied cytologically :1. Dendranthema (Asteraceae) : More than 600 individuals of Dendranthema were collected in 81 populations in 14 Provinces or Regions revealing the following chromosome numbers : 2n=18 in D. lavandulifolium var. lavandulifolium and D. lavandulifolium var. seticuspe (common to Japan) ; 2n=36 in D. indicum (common to Japan) and D. potentilloides ; 2n=36 and 54 in D. chanetii ; and 2n=54 in D. oreastrum, D. naktongense, and D. vestitum. A natural hybrid between D. indicum and D. vestitum was newly discovered. Cytogeographical maps were drawn. Artificial F_1-hybrids between Dendranthema vestitum endemic to China and eight taxa of Japanese Dendranthema species were successfully produced.2. Ajania (Asteraceae) : Five hundred and fifty individual-plants in approximately seven taxa of Ajania were collected in highlands in Sichuan Province. The chromosome numbers in three taxa were studied for the first time : 2n=18 in A. racemosa … More , 2n=36 in A. przewalskii and 2n=36 in A. tenuifolia.3. Aster ageratoides (Asteraceae) : Thirty-three populations of Aster ageratoides from 16 Provinces or Regions were studied cytologically. Aster ageratoides of China composes a polyploid complex of 2x (2n=18), 4x (2n=36), 6x (2n=54) and their natural hybrids similar in occurrence to that of Japan. The cytogeographical map of the A. ageratoides polyploid complex was drawn.4. Cyperaceae : About 40 species in seven genera of the Cyperaceae were collected from five Provinces ; of those 20 species were common to Japan. The chromosome numbers in nine species of Carex, Eleocharis, Scirpus and Kobresia were studied. The tetraploid (2n=24) Carex siderosticta was found to be distributed from Japan to Northeast China.5. The Orchidaceae and other families : The chromosome numbers in five species of the Orchidaceae from China were studied. Spiranthes sinensis (2n=30) and Goodyers procera (2n=42) of China were same in chromosome number to those of Japan. Some species of the Liliaceae and Paeonia (Paeoniaceae) were collected in Japan and studied cytologically by using chromosome banding techniques. Less