Nucellar embryony (notated Nu+) is a form of seedreproduction that occurs in certain plant species, including many citrusvarieties. During the development of seeds from plants that possess this genetic trait, the nucellar tissue which surrounds the megagametophyte can produce additional embryos (polyembryony) which are genetically identical to the parent plant. These nucellar seedlings are essentially clonesof the parent. By contrast, zygoticseedlings are sexually produced and inherit genetic materialfrom both parents. Zygotic and nucellar embryos can occur in the same seed, and a zygotic embryo can divide to produce multiple embryos.
In botany, apomixis was defined by Hans Winkler as replacement of the normal sexual reproduction by asexual reproduction, without fertilization.[
1]
This definition notably does not mention
meiosis. Thus "normal
asexual reproduction" of plants, such as propagation from cuttings or leaves, has never been considered to be apomixis, but replacement of the seed by a
plantlet, or replacement of the flower by
bulbils are types of apomixis. Apomictically produced offspring are genetically identical to the parent plant.
