The female cone produced megaspore mother cell is differenciated from one of the cells of the nucellus.The nucellus is protected by envelope & composite structure called an ovule . The megaspore mother cell divides meiotically to form four megaspores . One of the megaspores enclosed within the megasporangium and develops into a multicellular female gametophyte that bears two or more archaegonia of female sex organ . The multicellular female gametophyte is retained within the megasporangium.