Abstract: Accoding to its typical 4-merous flower, both terminal and lateral flower,Tetradoxa has been considered as the primitive genus in Adoxaceae. As a result, the long term contraversy about "invo1ucre-calyx" or "calyx-carolla" in Adoxa was settled here. According to this study, the rates of variation flowers in Adoxa moschatellina are much higher than the other 2 genera including 3 species in Adoxaceae. The rates of variant flowers in Adoxa moschatellina are 20% in terminal flowers and 36.1 % in lateral flowers. A reductive series by the reduction of poste-rior stamen and fusion of the adjacent carollamlobes from 6-merous to 3 merous of carolla and stamen exists in Adoxa only. The ancester form of Adoxaceae with both terminal and lateral flower is suggeted to be 2-merous. At Present, 3 genera including 4 species in the family seem to have been derived from the original 2-merous flower by multiplication (including diversity), reduction (in-cluding fusion) of the flower parts.

Key words: Adoxaceae