Abstract
Three sibling species of the Conocephalum conicum complex have been reported in Japan; J-type, F-type and S-type (the latter two were formerly named as a FS- and S-type, respectively). In this study, we report their chromosome numbers and karyotypes for the first time. Both male and female plants of the three species had the same chromosome number and karyotype [K (n)=9=5V+2J+j+m]. The m-chromosomes are much smaller than the others and thus difficult to detect. This is the possible reason why there had been several different reports on the chromosome numbers of Conocephalum conicum, i.e., n=8 or 10.
