Geographical Distribution of Sexual and Apogamous Types of Dryopteris chinensis (Dryopteridaceae) in Japan

Abstract

Only triploid and tetraploid apogamous cytotypes have previously been reported for the fern Dryopteris chinensis (Dryopteridaceae). In this paper we report the discovery of a diploid sexual cytotype of D. chinensis. The geographical distribution of the sexual and apogamous types of the species in Japan and adjacent region was determined by counting the number of spores per sporangium in a large number of herbarium specimens from MAK and TNS. Apogamous plants were found to be the predominant type in Japan; the sexual type was restricted to Miyazaki, Oita, and Kumamoto prefectures in Kyushu, and Kochi Prefecture in Shikoku, Japan.