Abstract: To explore the karyotype characteristics,evolutionary trends and phylogenetic relationships of dandelion in Hebei region. Karyotype analysis was conducted on 20 different geographical populations of dandelions in 5 regions of Hebei by using the method of conventional root tip compression. And cluster analysis was conducted on the similarity coefficient of karyotype and genetic distance. The results showed that the number of chromosomes in the 20 dandelions was 2n=24 or 32,and the chromosome number was x=8 or 12. There were diploids,homologous triploids,allotriploids,and allotetraploids. There were four types of karyotypes:1A,2A,1B,and 2B. Seventeen karyotype formulas,all with accompanying bodies. Asymmetric coefficient of karyotype AS.K% was between 56.54% and 61.32%,and the karyotype asymmetry coefficient AI was between 0.97 and 3.22. Z2 and C2 had the highest similarity coefficient in karyotype (0.997 8),the smallest evolutionary distance in karyotype (0.002 2),and the closest phylogenetic relationship. B2 and Z4 had the highest evolutionary distance in karyotype and the farthest phylogenetic relationship. When the similarity coefficient of karyotype was 0.985 7,20 different geographical populations of dandelions were grouped into five categories. When the similarity coefficient of karyotype is 0.661 8,belong to the same category. This study proved the karyotypes and phylogenetic relationships of different geographical populations of dandelions in Hebei,laid a cytological foundation for further exploration of the classification,systematic evolution,and phylogenetic relationships of dandelions.

Key words: Dandelion, Karyotype, Resemblance-near coefficient, Cluster analysis

摘要： 为探究河北地区蒲公英(Taraxacum F.H.Wigg.)的核型特征、进化趋势及亲缘关系。本研究采用常规根尖压片法对河北5个地区20个不同地理居群蒲公英进行核型分析及核型似近系数聚类分析。结果表明，20个蒲公英的染色体数目为2n=24，32，染色体基数x=8，12；有二倍体、同源三倍体、异源三倍体、异源四倍体。核型有1A，2A，1B，2B四种类型。17种核型公式，均有随体。核型不对称系数AS.K%在56.54%~61.32%之间，核型不对称系数AI在0.97~3.22之间。Z2和C2核型似近系数最大(0.997 8)，核型进化距离最小(0.002 2)，亲缘关系最近，B2与Z4的核型进化距离最大，亲缘关系最远。当核型似近系数为0.985 7时，20个蒲公英聚为五类，当核型似近系数为0.661 8时，共属一类。本研究探明了河北不同地理居群蒲公英的核型及亲缘关系，为进一步探明蒲公英的分类、系统进化、亲缘关系奠定细胞学基础。

关键词: 蒲公英, 核型, 似近系数, 聚类分析