Angiosperms are plants that have seeds encased in a protective covering. That covering is the ovary; it is the part of the flower structure. It distinguishes angiosperms from gymnosperms, the other seed plants. So it can be said that angiosperms are also flowering plants. The angiosperms may be divided into two classes: monocots and dicots. Angiosperms, like gymnosperms, are heterosporous, which means they produce two types of spores and their sporophytes are more dominant than those of gymnosperms. At maturity, the female gametophytes are reduced to a few cells and are completely enclosed within sporophyte tissue; while the male gametophytes consist of a binucleate cell with a tube nucleus which forms a pollen tube much like the one formed in gymnosperm pollination.