Abstract: In this paper, the origin and evolution of genus Camellia was discussed by cytogeographical method. The results were based on the information on chromosome numbers of 62 species and on karyotypes of 54 species in 10 sections, 52 and 45 of total species respectively. There was stable basis number (x = 15) and various ploidy (from 2x to 8x) in Camellia. Every section contained diploid and some of them were all diploid. Poly-ploid species were mainly in Sect. Camellia, Seci.Paraccimellia and Sect. Theopssis, and distributed in the north-east, west and north of distribution of Camellia, presenting the tendency that polyploid was more in the north and west than in the south. Karyotypical evolution in Camellia agreed with Stebbins theory, from symmetry to asymmetry. Sect.Archecamellia contained the most symmetrical karyotype and was the most primitive group in 10 sections; Sect. Camellia was the most advanced groups. Sect. Heterogenea, including C. yiavumensis, was not the most origninal group in Camellia, because of its high asymmetrical karyotype. Camellia might be origi-nated in Indochina Peninsula, then dispersed mainly to northern area and differentiated rapidly in the present distributio center ,Yunnan ,Guangxi and Guangdong ,and formed most speciees of Camellia

Key words: Camellia, Karyotype, Ploidy, Cytogeography

摘要： 本文收集整理了山茶属的细胞学资料，以细胞地理学的方法探讨该属的起源和演化。在山茶属14组119种植物中有10组62种已具染色体数目的报道，54种已知核型，分别占总数的52％和45％。山茶属植物具有稳定的基数 (x=15)和多变的倍性（2X→8X）。每一个组都有二倍体或全为二倍体；多倍体主要出现在Sect．Camallia、Sect．Paracamellia和Sect．Theopsis之中，大多分布在山茶属分布区的西部、北部和西北部，呈现出北多南少的趋势。山茶属的核型遵守Stebbins的从对称向不对称演化的规律，分布中心靠南的组比靠北的组拥有更对称的核型，表明山茶属从南向北进化和扩散。在已具核型资料的组中，Sect．Archecamellia最原始，Sect．Camellia最进化，包括C.yunnanensis的Sect．Heterogenea不可能是山茶属最原始的类群。我们认为山茶属很可能起源于中南半岛，主要向北扩散和进化，在现今的分布中心发生了快速的分化，形成了大量种类。

关键词: 山茶属, 倍性, 核型, 细胞地理学