Nucellar embryony is a term used to refer to a type of asexual reproduction in plants where an embryo is formed from nucellar tissue rather than from fertilization. Some alternative synonym terms for nucellar embryony include nucellar polyembryony, adventive embryony, and apospory. Nucellar polyembryony is a form of asexual reproduction in plants that results in multiple embryos forming from nucellus cells. Adventive embryony is a process where a new plant is formed from a part of a parental plant that is not a reproductive organ. Apospory is another form of asexual reproduction in plants where a mature sporophyte is formed from a gametophytic precursor without fertilization.