SUMMARYIt is known that in Taxus (Taxaceae) megasporogenesis is carried out, for the most part, in a single megasporocyte. Upon maturity, this cell presents a grouping of the greater part of both the mitochondria and the amylipherous reserves in its chalazal cytoplasm. The chalazal megaspore, which inherits a larger supply of the said organelles, gives rise to the female gametophyte. These aspects essentially agree with what has been generally observed in gymnosperms. Nevertheless, research carried out under the LM shows that in Taxus there is—even if sporadically—differentiation of several megasporocytes. Moreover, the behaviour of the kinoplasmic mass is variable and any of the megaspores arising from the same meiotic act can be the functional one. Finally, more than one megaspore, even up to four, can begin to develop. The aim of this investigation was to identify in the megasporocyte of Taxus baccata L. the possible ultrastructural bases for the afore-mentioned uncommon aspects. The most significant n...