Chromosome Studies in Cyperaceae, VIII

Abstract

1) The maturation divisions of diploid and tetraploid forms of Carex siderosticta Hance have been described. From the cytological and morphological points of view the tetraploid in question has been concluded to be autotetraploid.2) Chromosome behavior in meiosis of the diploid was quite regular, while that of the tetraploid was accompanied by some irregularities as seen in the case of general autotetraploids. Meiotic irregularities seen in the tetraploid are chiefly due to irregular separation of the multivalents present at IM.3) In the tetraploids, owing to the meiotic irregularities, about 30% of the gametes observed were unbalancing, and reduction in fertility was observed.4) Factors which may be concerned to the reduced fertility in the autotetraploids and their significance for the aneuploidy in the genus Carex have been discussed.Here the writer wishes to express his best thanks to Prof. Y. Sinoto, by whose suggestion these studies were started, for his valuable advice throughout the course of the work. A part of the expenses of this work was defrayed out of a grant from the Japan Society for the Promotion of Scientific Research.