小花三脉紫菀和狭叶三脉紫菀的区别:形态学和细胞学证据

产自湖北神农架的狭叶三脉紫菀Aster ageratoides var. gerlachii (Hance) Chang一直被各种文献和有关标本馆误定为小花三脉紫菀A. ageratoides var. micranthus Ling。我们对二者进行了野外采集和形态学、细胞学的比较研究,分析了导致错误鉴定的原因,重新确定了二者的界限。小花三脉紫菀无横走地下茎,这一性状具有重要的分类学价值。核型研究发现,小花三脉紫菀为二倍体,2n=2x=18=18m,核型属1A型;狭叶三脉紫菀则是四倍体,2n=4x=36=32m+4sm (2SAT),核型属2A型。二变种的染色体数目、核型均为首次报道。狭叶三脉紫菀在湖北为新分布记录。

Differentiation between Aster ageratoides var. micranthus and var. gerlachii: evidence from morphology and cytology

Collections of Aster ageratoides var. gerlachii (Hance) Chang from Shennongjia, Hubei Province, central China, have long been erroneously referred to A. ageratoides var. micranthus Ling. A comparative study on the morphology and cytology of the two varieties was conducted to gain a better understanding of their relationships. The possible factors causing the misidentification are discussed and the diagnostic characters between the two varieties are redefined. The absence of horizontal rhizome in var. micranthus was found to be of important taxonomic value. A. ageratoides var. micranthus was a diploid with the karyotype formula of 2n=2x=18=18m, with the karyotype belonging to 1A type in karyotypic asymmetry, whereas A. ageratoides var. gerlachii was a tetraploid with the karyotype formula of 2n=4x=36=32m+4sm (2SAT), with the karyotype belonging to 2A type. A. ageratoides var. gerlachii is a newly recorded taxon in Hubei.