Karyotype Analysis of Eight Species of Polygonatum Mill.
黄精属八种植物的染色体研究

Meiosis and mitosis of eight species of Polygonatum from Sichuan, China, were investigated. Ten bivalents (n=10) at meiosis of pollen mother cells were observed ih P. od- oratum (Mill.) Druce. Meiotic observation on pollen mother cells in P. punctatum Royle ex Kunth shows 16 bivalents (n=16) at diakinesis, P. kingianum Coll. et Hemsl. 13 bivalents (n=13) at diakinesis. P. zanlanscianense Pamp. 15 bivalents (n=15) in MI, P. cirrhifolium (Wall.) Royle 28 bivalents at diakinesis. Somatic chromosomes were observed in root tip cells. The karyotype formulae are as follows: P. odoratum (Mill.) Druce K(2n)=20=4st+6sm+10m; P. cyrtonema Hua K(2n)=20=6sm+14m; P. punctatum Royle ex Kunth K(2n)=32=2t+8st+ 2sm+20m; P. kingianum Coll. et Hemsl. K(2n)=26=8st(2SAT)+14sm+4m; P. alternicirrho- sum Hand.-Mzt. K(2n)=32=6st+8sm+18m(2SAT); P. zanlanscianense Pamp. K(2n)=30= 2t+6st+6sm+16m(2SAT); P. sibiricum Delar. ex Redouté K(2n)=24=2t+14st(2SAT)+6sm +2m; P. cirrhifolium (Wall.) Royle K(2n)=56=18st+10sm+28m. The karyotypes of P. punctatum, P. kingianum, P. alternicirrhosum and P. cirrhifolium are reported for the first time. Both the chromosome number and structure in our materials are certainly different from thoses in previous reports. Of numerical variation polyploidy and aneuploidy have been record- ed, and aneuploidy is frequent. According to degree of asymmetry of the karyotype, the 8 species are divided into three types: 2B, 3B, 2C. The increasing asymmetry is correlated with the increasing of the chromosome number. There are no obvious differences in chromosome number and karyotype between Alterni- folia Baker and Verticillate Baker. They are not two natural groups. This opinion is dif- ferent from that of Therman and Suomalainen.