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Apomixis: It is derived from two Greek words APO (away from) and mixed ( the act of mixing or mingling). It refers to the occurrence of an asexual reproductive process in the place of normal sexual processes involving reduction division and fertilization.

Types of Apomixis:- Three types of apomixis are generally recognized – diplospory, apospory and adventitious embryony. These apomictic processes are depicted compared to sexual processes in the formation of a common Polygonum-type embryo sac.

1. Diplospory: In diplospory, the unreduced embryo sac is derived from the megaspore mother cell either directly by mitotic division or by aborted meiotic events. Three major types of diplospory have been reported, named after the plants in which they occur, and they are the Taraxacum, Ixeris and Antennaria types.
2. Apospory :In apospory, the nuclear cells that give rise to the apomictic embryo sac, termed aposporos initials, are distinct from the ameiotic megasporocyte. They are similar in appearance to the ameiotic megasporocyte and may differentiate close to the ameiotic megasporocyte and develop into an apomictic embryo sac.
3. Adventitious Embryony: In this process, embryos initiate parthenogenetically outside of an embryo sac structure. Adventitious embryony is most commonly initiated later in ovule development from nucellar and integumentary tissues.

In general, fertilization in the adjoining sexual embryo sac and subsequent endosperm formation is necessary to form viable seeds. The developing embryos closest to the embryo sac grow towards it, presumably to obtain nutrient and other developmental signals from the embryo sac.