The proper formation and development of shoot apical meristem during plant embryonic development is prerequisite to generate leaves,buds and stems.Rice(Oryza sativa L.) mutant line 4001 produces multiple plumules in one seed and is consi dered as an important mutant with abnormal differentiation of shoot apical meristem.While the embryonic basis of the mutant with multiple plumules is yet unknown.To elucidate the cytological basis,mature embryo sac structure and process of double fertilization were observed...