Editing Apomixis (section)

====Types of gametophytic apomixis====
Gametophytic apomixis in flowering plants develops in several different ways.<ref name=Nogler>Nogler, G.A. 1984. Gametophytic apomixis. In Embryology of angiosperms. Edited by B.M. Johri. Springer, Berlin, Germany. pp. 475–518.</ref> A megagametophyte develops with an egg cell within it that develops into an embryo through [[parthenogenesis]]. The central cell of the megagametophyte may require fertilization to form the [[endosperm]], '''pseudogamous gametophytic apomixis''', or in '''autonomous gametophytic apomixis''' endosperm fertilization is not required. 
*In '''diplospory''' (also called '''generative apospory'''), the megagametophyte arises from a cell of the [[archesporium]].
* In '''apospory''' (also called '''somatic apospory'''), the megagametophyte arises from some other (somatic) cell of the nucellus.

Considerable confusion has resulted because diplospory is often defined to involve the [[megaspore mother cell]] only, but a number of plant families have a multicellular archesporium and the megagametophyte could originate from another archesporium cell.

Diplospory is further subdivided according to how the megagametophyte forms:
* ''[[Allium]] odorum''–''A. nutans'' type. The chromosomes double (endomitosis) and then meiosis proceeds in an unusual way, with the chromosome copies pairing up (rather than the original maternal and paternal copies pairing up).
* ''[[Taraxacum]]'' type: Meiosis I fails to complete, meiosis II creates two cells, one of which degenerates; three mitotic divisions form the megagametophyte.
* ''[[Ixeris]]'' type: Meiosis I fails to complete; three rounds of nuclear division occur without cell-wall formation; wall formation then occurs.
* ''[[Blumea]]''–''[[Elymus (plant)|Elymus]]'' types: A mitotic division is followed by degeneration of one cell; three mitotic divisions form the megagametophyte.
* ''[[Antennaria]]''–''[[Hieracium]]'' types: three mitotic divisions form the megagametophyte.
* ''[[Eragrostis]]''–''[[Panicum]]'' types: Two mitotic division give a 4-nucleate megagametophyte, with cell walls to form either three or four cells.