Abstract: Embellum of Apluda mutica was studied by light microscope. It was demonstrated that outer layer of 1-3 nucellar cells which enlarge in size and often protrude into the micropyle to form embellum at the functional megaspore stage. Both polygonum type and panicum type embryo sac have embellum. The length of embellum is about one to three times of its width in mature aposporous embryo sac, while its length is one to two times of its width in mature sexual embryo sac. The mature embellum cells in aposporous embryo sac were larger than that in sexual embryo sac. The larger embellum could be used as a secondary screening indicator for identifying aposporous embryo sac in Apluda mutica.