Abstract
The writers studied the chromosome numbers in 26 species or varieties of Gramineae which flower mainly from spring to summer in the northern part of Kantô district.
1). The basic number of chromosomes is 7 with the exceptions of 4 species that have 9 or 10 in haploid.
2). 30 percent of grass materials was revealed to be diploid, 50 percent tetraploid, 10 percent hexaploid and 10 percent octoploid. Thus the polyploids, especially the tetraploid are predominant in this district from spring to summer.
3). It was found that, in the genus Agropyron, the high polyploid species are to be more adaptable in high elevation than the related lower polyploid ones.
4). Some grasses naturalized from the cultivation showed high polyploidy.
5). In the genera Agropyton, Agrostis, Bromus and Poa, the higher polyploid species are more useful for the forage plant than the lower polyploid ones.
