蟛蜞菊属和孪花菊属(菊科-向日葵族)的细胞学研究

Cytology of Sphagneticola and Wollastonia,Two Genera in Heliantheae,Asteraceae

研究了菊科向日葵族鳢肠亚族蟛蜞菊属(Sphagneticola O.Hoffm.)和孪花菊属(Wollastonia DC.ex Decne.)各2种植物的染色体数目和染色体形态。蟛蜞菊[S.calendulacea(L.)Pruski]的染色体数目为2n=50,核型公式为2n=18m+30sm+2st,南美蟛蜞菊[S.trilobata(L.)Pruski]的染色体数目为2n=56,核型公式为2n=24m+28sm+4st,孪花菊[W.biflora(L.)DC.]的染色体数目为2n=30,核型公式为2n=24m+4sm+2st,山孪花菊[W.montana(Blume)DC.]的染色体数目为2n=74,核型公式为2n=37m+31sm+6st。根据上述结果并结合以前的有关资料,推测蟛蜞菊属的染色体基数可能为x=14和x=25,而不应是x=15。该属的3个新世界热带种[S.brachycarpa(Baker)Pruski、S.gracilis(Richard)Pruski和南美蟛蜞菊]可能都基于x=14,其中S.gracilis为二倍体(2n=2x=28),S.brachycarpa和南美蟛蜞菊为四倍体(2n=4x=56);唯一的亚洲种(蟛蜞菊)可能是基于x=25的二倍体(2n=2x=50)。染色体资料不支持将山孪花菊(x=37)这一植物置于孪花菊属(x=15)中。

Chromosome number and chromosome morphology in Sphagneticola O.Hoffm.and Wollastonia DC.ex Decne.,two small genera in Ecliptinae,Heliantheae,Asteraceae,were investigated.The results showed that the karyotype formula were followed as： Sphagneticola calendulacea（L.） Pruski,2n=50=18m＋30sm＋2st,S.trilobata（L.） Pruski,2n=56=24m＋28sm＋4st,Wollastonia biflora（L.） DC.,2n=30=24m＋4sm＋2st,and W.montana（Blume） DC.,2n=74=37m＋31sm＋6st.Based on the results,together with chromosomal data previously reported in Sphagneticola,we postulate the basic chromosome numbers of this genus as x=14 and x=25,rather than x=15.The three species native to the New World tropics in the genus,namely S.brachycarpa（Baker） Pruski,S.gracilis（Richard） Pruski and S.trilobata,may be based on x=14,with S.gracilis being diploid（2n=2x=28）,and both S.brachycarpa and S.trilobata tetraploid（2n=4x=56）;the only Asian species,S.calendulacea,may be diploid（2n=2x=50） based on x=25.The systematic implication of this chromosome number pattern is worthy of a further study.Chromosomal data do not support the placement of W.montana（x=37） in the genus Wollastonia（x=15）.