| Abstract: | The present paper deals with the cytological investigation of Taiwania flousianaGaussen. The somatic chromosomes in root-tip cells of the plant are found to be 2n=22 forthe first time, all with median and submedian constrictions. According to the terminology defined by Levan et al.[11], the karyotype formula is K(2n)=16m+6sm, which belongs to “2B”of Stebbins'[16,17] karyotypic symmetry and is generally regarded as a relatively primitive one.The species' chromosome complement is 2n=22=4L+6M2+8M1+4s according to the standarddefined by Kuo et al.[10] based on relative length. The nucleolus number in resting root-tip cells of T. flousiana is found to be 1-5 (Table3). The percentage of cells with two nucleoli is 77.6%, and those with five nucleoli, the highestnumber ever found by me, is only 1.6%. A few cells with many micronuclei are found in thisspecies for the first time (Plate 1, 1). Although T. flousiana and T. cryptomerioider have the same “2B” type of karyotypicsymmetry, the differences in the arm ratio and the index of the karyotypic asymmetry (Table2) show that the karyotype of the former is less symmetrical than that of the latter, so theformer may be a little more advanced than the latter. The basic karyotype (2B) of Taiwania is more related to that of Cunninghamia (1B)[3]than to that (1A) of Metasequoia[5], Glyptostrobus[4] and Cryptomeria[3]. Wang et al.[1], havereached the similar conclusion from the embryological study. |
