Cytotaxonomically investigated in this work were 6 species in 4 genera of
Polygonateae (sensu Krause, 1930). Each species was karyotypically analysed using 5 so-
matic metaphase cells with well-spread chromosomes. The chromosome classification follows
Levan et al. (1964) and the karyotype classification is according to Stebbins (1971). The ma-
terials used are listed in the Appendix and the vouchers are deposited in PE. The chromosome
numbers and karyotypes of Disporum megalanthum and Disporopsis aspera are reported here
for the first time, and those of Chinese Maianthemum bifolium are also reported for the first
time. The results are shown as follows.
(1) Disporum Salisb. D. megalanthum Wang et Tang from tthe Wolong
Nature Reserve, Sichuan, is found to have a karyotype 2n=16=2m(1SAT)+6sm(1SAT)+8st
(3SAT) (Plate I, A). The parameters of chromosomes are listed in Table 1 and the idiogram
is shown in Fig. 1, A. The chromosomes range in length from 8.5 to 29.3 μm, with the ratio
of the longest to the shortest 3.45. The karyotype belongs to Stebbins' (1971) 3B. In a somatic
chromosome complement the 2nd, 4th, 6th and 7th pairs each have one chromosome carrying
a satellite, showing heterozygosity.
Another material from the Qinling Range, Shaanxi, is shown to have 2n=16=2m(1SAT)
+8sm(3SAT)+6st (Plate 1, B). The parameters of chromosomes are listed in Table 1 and
the idiogram is presented in Fig. 1, B. The chromosomes range in length from 6.3 to
22.6μm, with the ratio of the longest to the shortest 3.61, and thus the karyotype belongs to
3B. The karyotype shows clear heterozygosity (Fig. 1, B). The two chromosomes of the first
pair have arm ratios 2.38 and 1.82 respectively, but they are equal in length, 22.6 μm. It seems
to us that a pericentric inversion has taken place in one of the two chromosomes. Moreover,
the 3rd and 4th pairs each have one chromosome carrying a satellite attached to the long arm.
These two materials are of the basically same karyotype, the major difference between
them being that the 3rd pair in the former consists of two st chromosomes with the arm ratio
3.15, while the corresponding pair in the other is of two m chromosomes with an arm ratio
1.67.
Seven East-Asian species of the genus Disporum are reported to have 2n=14, 16 and 18
(or 16+2B?), but 2n=16 is common to all the species, and therefore the basic number of the
group is x=8. For the North American group of the genus, however, 3 species (D. hookeri,
D. lanuginosum, D. oreganum) are of 2n=18, D. smithii is of 2n=16, and D. maculatum
2n=12. Chromosome numbers are more variable in the North American group, but x=9 seems
to be a dominant basic number. Even more striking difference in karyotype between the
two groups exists in size of chromosomes, 2.0-4.9μm.for the North American group, while 4.0-
16.0 μm for the East-Asian counterpart (Therman, 1956) (Our result shows 6.3-22.6 μm and
8.5-29.3 μm for the two materials). This remarkable contrast in karyotype is clearly correlat-
ed with the differentiation in gross morphology. The East-Asian species have calcarate tepals
but no reticulate veins of leaves, whereas the North American ones have reticulate veins but
spurless tepals. The evidence from karyotype and morphology seems to justify the restoration
of the genus Prosartes for the Nortth American species (Conover, 1983, cf. Dahlgren et al.
1985).
(2) Disporopsis Hance D. pernyi (Hua) Diels from Mapien, Sichuan, is of
2n = 40 = 23m(2SAT)+13sm(2SAT) + 2st+ 2t(2SAT) (Plate 1, C). The parame-
ters of chromosomes are listed in Table 2, and the idiogram is shown in Fig. 2, A.
The chromosomes range in length 5.2-16.2μm, with the ratio of the longest to the
shortest 3.11, and thus the karyotype belongs to 2B.
D. aspera (Hua) Engl. ex Krause also from Mapien, Sichuan, is found to have
2n=40=30m+8sm(2SAT)+2t(2SAT) (Plate 1,D). The parameters of chromosomes are listed
in Table 2, and the idiogram is shown in Fig. 2, B. The chromosomes range in length 5.2-
14.7 μm, with the ratio of the longest to the shortest 2.84. Therefore, the karyotype belongs to
2B. Another material from the same locality but different population was also examined and
found to have 2n=40=30m+6sm+2st(2SAT) (Fig. 2, C).
D. arisanensis (=D. pernyi) from Taiwan is reported to have 2n=40=26m+12sm+2st
(Chang and Hsu, 1974), D. fusco-picta from the Philippines 2n=40=22m+16sm+2st(2SAT)
(Kumar and Brandham, 1974), and D. longifolia from Thailand 2n=40 (Larsen, 1963). Thus,
the species in the genus, except the newly described D. jingfushanensis Z. Y. Liu (1987) with
no chromosome data, are all of 2n = 40, and the basic number of the genus is x = 20. From
the karyotype formulae, asymmetry of the karyotypes increases from D. aspera to D. fusco-picta
through D. pernyi, which may be correlated with the increasing specialization of gross morpho-
logy.
(3) Maianthemum Web. M. bifolium (L.) F. W. Schmidt from the Qinling
Range, Shaanxi, is found to have 2n = 36 = 20m + 10sm + 4st + 2t (2SAT) (Plate
1, H). The parameters of the chromosomes are listed in Table 3, and the idiogram
is shown in Fig. 3, D. The chromosome lengths range 2.4-8.2μm, with the ratio
of the longest to the shortest 3.43. The karyotype thus belongs to 2B, and is sligh-
tly bimodal: the first 10 pairs and the pair of sat chromosomes are larger than the
rest 7 pairs, the ratio of the shortest in the former group to the longest in the latter
group being 1.24.
(4) Polygonatum Mill. P. humile Fisch. ex Maxim. from Chicheng County,
Hebei, is shown to have a karyotype 2n= 20= 10m(2SAT)+6sm(2SAT)+ 4st
(Plate 1, G). The parameters of chromosomes are listed in Table 4, and the hap-
loid idiogram is shown in Fig. 3, C. The chromosome lengths range from 3.0 to
10.0μm with the ratio of the longest to the shortest 3.3. The karyotype therefore
belongs to 2B.
P. odoratum (Mill.) Druce Two materials in this species were examined. One from
Chicheng County, Hebei, has 2n=20=10m+10sm(3SAT) (Plate 1, E). The parameters of
chromosomes are presented in Table 4 and the somatic idiogram in Fig. 3, A. The chromoso-
mes range in length 3.1-8.8 μm, with the ratio of the longest to the shortest 2.8. The karyo-
type is thus of 2B. The other from the Qinling Range, Shaanxi, is found to have 2n=20=
12m(4SAT)+8sm(2SAT) (Plate 1, F). The parameters of chromosomes are listed in Table
4, and the haploid idiogram is shown in Fig. 3, B. The chromosomes range in length 4.2-
10.9 μm, with the ratio of the longest to the shortest 2.6. The karyotype is also of 2B.
P. odoratum is widely distributed in Eurasian temperate region and its cytological reports
are frequently seen. All the materials outside of China, from Portugal to Japan, are reported
to have 2n=20, except one material from east Sayan in SE Siberia, which is reported to have
2n=30 (Krogulevich, 1978). In China, however, three chromosome numbers have so far been
reported under the name P. odoratum, 2n=20 from the Changbai Mountains, Jilin Province
(Fang, 1989), Qinlong County, Hebei Province (Wang et al. 1987), the Jinfo Mountains, Si-
chuan Province (in cultivation), besides the two materials used in this work; 2n=22 from Mt.
Jinshan in Beijing (Li, 1980), Wuhan in Hubei Province, Yixin in Jiangsu Province and Mt.
Emei in Sichuan Province (Fang, 1989); 2n=18 from Yixin in Jiangsu Province and the Dabien
Mountains in Anhui Province (Fang, 1989). It is, therefore, rather evident that the species
under discussion is variable in chromosome number only in the southern part of its distribution
area. Karyotypical morphology is also variable in this species. The 2n=20 group is found to
have following karyotypes: 12m(4SAT)+8sm (in Austria, Hong et al. unpubl.), 14m+6sm
(Jilin): 12m+8sm (Qinlong, Hebei): 10m+10sm (3SAT) (Chicheng, Hebei): 12m(4SAT)+
8sm(2SAT) (Shaanxi) and 10m+6sm+4st(Mt. Jinfo, Sichuan). For the 2n=18 group, 10m+
8sm (Anhui) and 8m+10sm (Jiangsu) have been found. In the 2n=22 group these karyotype
formulae so far reported are all 10m+8sm+4st. Comparing the karyotypes in the three groups
we find that 4st chromosomes are always present in the 2n=22 group, while in the other two
groups, except the karyotype 10m+6sm+4st found from the Jinfo Mountains in Sichuan, all
the karyotypes consist of m and sm chromosomes.
Based on the correlation between karyotypical data and cryptic morphological differences
Wang et al. (1988) consider Polygonatum odoratum as a complex, which consists of three
species: Polygonatum odoratum (s. str. 2n=20), P. macropodium Turcz. (2n=22) and P. simi-
zui Kitag. (2n=18). But in this complex biosystematic problems, such as relationship between chromosome number and chromosome structure, evolutionary relationship of the different chromosome numbers, relationship between means of reproduction (extent of vegetative propagation) and karyotype variation are still unresolved and deserve further studies.
