macrospore

But the formation of the macrospore or embryo-sac is simpler than the corresponding process in cryptogams.

The larger ones contain each a large spore, or macrospore; the smaller contain numerous microspores, immersed in mucilage.

The macrospore divides into two cells, a large lower one, and a smaller upper one.

The nucellus is a cellular tissue enveloping one large cell, the embryo-sac or macrospore.