广义紫菀属(菊科紫菀族)系统学研究的现状

Present Status of Systematical Studies on Aster s.l.(Astereae,Asteraceae)

广义的紫菀属(Asters.l.)曾是个大包大揽的类群,产于北美和欧亚大陆.Nesom主要根据瘦果的形态和细胞学性状对Asters.l.进行了评价,将北美紫菀类植物从Aster中独立出去,使Aster成为欧亚特有类群.但是,在欧亚各国对Aster有定为一属和分为十多个属等不同的分类学处理,分歧较大.狭义紫菀属(Asters.s.)与从Asters.l.中分出的各属之间的系统学关系,以及后者中某些属与北美紫菀类和紫菀族其他亚族间的系统学关系,都存在很大疑问.过去一直认为北美是Aster的发源地,现在欧亚Asters.l.的起源与演化需要重新研究,而青藏高原是探讨Asters.l.物种多样性形成的关键地区.DNA尤其是DNA序列资料在研究Asters.l.的系统发育和分类上将发挥关键作用.

In the traditional taxonomic treatment,Aster s.l.was a “catch all”group distributed in North America and Eurasia.On the basis of achene morphology and cytology of Aster s.l.,Nesom split North American asters from Aster s.l..As a result,Aster s.l.becomes a taxon or a group of genera endemic to Eurasia.However,there is great taxonomical confusion in Eurasian Aster s.l.for in different countries it is treated as one genus or as more than 10 genera.There are many problems in the relationships among Aster s.s.and the genera that were split from Aster s.l.,and among some of these genera and North American asters or other subtribes of Astereae.Furthermore,North America was viewed as the origin center of Aster s.l.,but now Qinghai Tibet Plateau becomes the area key to research on the formation of species diversity of Aster s.l.when the origin and evolution of Eurasian Aster s.l.becomes a new problem.On the other hand,DNA data,especially DNA sequence data,will play a key role in studies on the phylogeny and taxonomy of Aster s.l..