The double fertilization is only noticed in the angiosperms. The mature embryo sac is 8 nucleate stage and rest of the growth and changes occurs only after the process of fertilization. As a result of fertilization the zygote is formed which develops into embryo. The endosperm will provide nutrition for the developing embryo. The seeds which are formed by syngamy without triple fusion or by triple fusion without syngamy both of them are non-viable. Thus for the formation of a viable seeds both the fertilization i.e. the double fertilization is essential.