Agamospermy asexual reproductive process in the place of normal sexual processes involving reduction division and fertilization. Apomixis is widely distributed among higher plants. More than 300 species belonging to 35 families are apomictic. It is most common in Gramineae, Compositae, Rosaceae, and Rutaceae. Among the major cereals maize, wheat, and pearl millet have apomictic relatives. Different types of apomixis are
- Diplospory – The unreduced embryo sac is derived from the megaspore mother cell either directly by mitotic division or by aborted meiotic events.
- Apospory – The nuclear cells that give rise to the apomictic embryo sac, termed aposporos initials, are distinct from the ameiotic megasporocyte.
- Adventitious Embryony – In this process, embryos initiate parthenogenetically outside of an embryo sac structure.
- Recurrent apomixis – In recurrent apomixis, both the egg-cell and embroyo are diploid and the embroyosac is developed from the megaspore mother cell.
- Non – recurrent apomixis – In non-recurrent apomixis, both the egg-cell and embroyo are haploid and embroyo is developed directly from an egg-cell without fertilization.
- Vegetative Apomixis – In this apomixis type, vegetative bulbils or buds are produced in the inflorescence instead of flowers.