Abstract: Chromosomes of 13 species in the genus Dryopteris Adanson (Dryopteridaceae) from Yunnan, China have been counted. The numbers in four species, D. alpestris Tagawa (2n=82), D. habaensis Ching (2n=82), D. lachoongensis (Bedd.) Nayar & Kaur (2n=82), and D. yungtzeensis Ching (2n=82), were reported for the first time. The triploid apomict D. rosthornii (Diels) C. Chr. (2n=123), the tetraploid apomict D. wallichiana (Spreng.) Hylander (‘n’=164, 2n=164) and the diploid apomict D. yoroii Serizawa (2n=82) represent three new cytotypes. Our results support the establishment of the section Caespitosae S. G. Lu, and indicate a high percentage of the diploid apomict cytotype in Dryopteris from the Himalayan region of China. The phenomenon of the presence of different cytotypes in a same plant of fern species is discussed.

Key words: Dryopteris, chromosome number, cytotype, cytotaxonomy