Abstract: The development of the endosperms of Trillium begins in the chalaza end. The first division of the cndosperm nucleus is accompanies by the formation of a horizontal wall which divides the embryo sac into two, usually unequal, chambers of which the micropylar one is larger than the chalazal. This is followed by several nuclear divisions in the micropylar chamber where the resulting nuclei remain free, while in the chalazal chamber the nucleus does not divide or occurs a few of divisions. In the course of further development, the nuclei in the chalazal chamber begin to disintegrate. Cell walls may appear in the micropylar chamber. Hence, the endosperm of Trilliumis of Holobial type.