A KARYOTYPICAL STUDY OF THE 4 SPECIES OF GENUS VIBURNUM

The present paper deals with a karyotype study of the 4 taxa of genus Viburnum. The chromosome numbers and karyotypic formulas of the species are as follows:V. dilatatum Thunb. and V. setigerum Hance:K(2n)=18=4M+2SM+10m+2sm V. foetidum Wall var. rectangulatum (Graebn.) Rehd.:K(2n)=18=4M+2SM+10m+2sm(SAT) V. ichangense (Hance) Rehd.:K(2n)=18=4M+2SM+10m+2t.The above information is reported for the first time.The 4 species belong to the same section of the genus Viburnum and are morphologically similar to each other. Results obtained through chromosome examination have shown that they also have a similar karyotype. According to Stebbins' classification of karyotype asymmetry, they all are classified to "Karyotype 2B". Therefore, it is suggested that the karyotypic pattern of sect. odontotinus is:K(2n)=18=4M+2SM+10m+2sm(or 2t).To compare the karyotype of Sect. Odontotinus with that of V. macrocephalum (Sect. Viburnum) and V. sympodiale (Sect. Pseudotinus), a great difference among them would be found though they all are bimodal karyotype, all the species of Sect. Odontotinus having two pairs of chromosomes with submedian centromeres or one pair of submediocentric chromosome and one pair of telocentric chromosome;V. macrocephalum having only one pair of chromosome with submedian centromeres, but in the complement of V. sympodiale all the centromeres being median.