Cytological Studies of 25 Species and Four Varieties of (Asteraceae) from China, Toward a Better Understanding of the Variation Patterns of Chromosomes in the Genus.

The chromosome numbers of 56 populations belonging to 25 species and 4 varieties of L. (Asteraceae) from China were examined, and those of 13 species and four varieties are reported here for the first time. The karyotypes of 39 populations in 23 species and four varieties were also studied. Among them, twelve species and one variety were found to be diploid, with 2 = 16 or 18; nine species and three varieties were found to be tetraploid, with 2 = 32 or 36; and two species were found to have both diploid and tetraploid cytotypes. Two species were found to have aneuploid cytotypes. The karyotypes of are similar, with most chromosomes belonging to median-centromeric (m) and a few belonging to submedian-centromeric (sm) or subterminal-centromeric (st). The high level of polyploids in from the Qinghai-Tibetan Plateau indicates that polyploidy has played an important role in the evolutionary speciation of this highly diversified genus in this region.