Abstract: Somatic chromosome numbers of 37 forms (representing 22 species) of apples in China were counted using wall-degradation and hypotonic method. Among the species investigated 3 categories of chromosome numbers, i.e. 2n=34, 51 and 68 are confirmed. The chromosome numbers of the following species are here first reported: Malus ombrophila 2n= 34, M. prattii 2n=34, M. melliana 2n=34, Zhaojiaohonghua (M. sp.) 2n=34, and M. asiatica var. 2n=68. Polyploids (including infraspecific polyploids) account for 41% of the total number of the species investigated. 51 is a predominant number. It is suggested that ploidy variation is an important pathway in apple evolution in China, and triploid may be considered as a suitable evolution grade. There are rich apple germplasm resources in China. The systematic studies of this genus are obviously essential.

Key words: Malus, Chromosome number, Polyploid