Abstract: Karyotype was studied via squash method in seventeen chrysanthemum cultivars with small inflorescences which differ in plant architecture and purpose. Karyotypic findings showed that all cultivars were mixoploid with chromosome number ranging from 49 to 57, and 54 was the most frequent number observed. In addition, diversity of chromosome morphology was observed. Metacentric, submetacentric and acrocentric chromosomes coexisted in most cultivars. The ratio of chromosome length, i.e., ratio of the length of the longest chromosome to that of the shortest one, varied from 1.62 to 2.39. The percentage of chromosome with arm ratio beyond 2 was between 11.11% and 29.62%. Asymmetry index (As.K%) ranged from 59.74% to 63.37%. The karyotypes of Dendranthema*grandiflorum 'Aoyunchengguang', 'Jinlingbaifeng'(2n=53) and three ground cover cultivars were characterized as "2B" type, whereas, those of the remaining cultivars were characterized as "2A" type. Karyotype diversity not solely resulted from the mutation of chromosome, recombination of chromosome also likely contributed to the diversity.

Key words: Dendranthema*grandiflorum, chrysanthemum with small inflorescences, chromosome number, karyotype, diversity