The present paper, mainly dealing with phytogeographical, Cytological and Palynolo

gical studies on Chinese Stachyuraceae, is the first part of a series of contributions to systematics of this family. As we know, Stachyuraceae, a monogeneric family, is  endemic to

East Asia, with a strong differentiation in China. Systematic position of the family is still uncertain. Undoubtedly, multidisciplinary studies on it wisl give a better understanding of plant differentiation in East-Asiatic floristic region and systematic position of the family.

     The distribution of all the 9 Chinese species of Stachyurus have been studied on the basis of morphogeographical method. The status of some taxa has been changed as follows: Stachyurus chinensis Franch. ssp. latus (Li) Y. C. Tang et Y. L. Cao, stat. nov. S. chinen-sis Franch. Ssp. cuspidatus (Li) Y. C. Tang et Y. L. Cao, stat. nov. S. chinensis Franch. ssp. brachystachyus (C. Y. Wu et S. K. Chen) Y. C. Tang et Y. L. Cao, stat. nov. S. salicifolius Franch. ssp. lancifolius (C. Y. Wu) Y. C. Tang et Y. L. Cao, stat. nov., S. yunnanensis Franch. var. pedicellatus Rehd. and S. oblongifolius Wang et Tang being reduced as synonyms of S. yunnanensis Franch. From morphological point of view, we would consider that sect. Callosurus is more primitive and its present area might be the preservation center of the family.

     In this paper the chromosome numbers of 5 taxa, i.e. Stachyurus yunnanensis, S. chinensis ssp. chinensis, S. chinensis ssp. cuspidatus, S. salicifolius ssp. salicifolius, S. retusus, are reported for the first time. Along with the chromosome countings of S. himalaicus and S. sigeyosii by S. kurosawa, we come to the conclusion that all the species so far studied have 24 small somatic chromosomes (2n=24).

     The pollen grains of 6 taxa, i.e. Stachyurus yunnanensis, S. obovatus, S. himalaicus, S. chinensis ssp. chinensis, S. salicifolius ssp. salicifolius, S. retusus were also examined. Together with the observations of G. Erdman and Huang Tsengchien on  S. himalaicus, it seems that the pollen grains of the genus Stachyurus are rather uniform in  morphology. The pollen grains of sect. Callosurus are tricolporoidate, while those of sect. Stachyurusare tricolporate. Two pollen types, representeb by the two sections, though not strongly distinct, may be considered as further evidence of the validity of the two taxa as section.

      Sexuality of flowers is also disscussed in the paper. According to our observation