Types of apomixis in flowering plants
Non-recurrent apomixis : In this type “the megaspore mother cell undergoes the usual meiotic divisions and a haploid embryo sac meqagametophyte is formed. The new embryo may then arise either from the egg (haploid parthenogenesis) or from some other cell of the gametophyte (haploid apogamy).” The haploid plants have half as many chromosomes as the mother plant, and “the process is not repeated from one generation to another”
(i) Recurrent apomixis, is now more often called gametophytic apomixis : In this type, the megagametophyte has the same number of chromosomes as the mother plant because meiosis was not completed. It generally arises either from an archesporial cell or from some other part of the nucellus.
(ii) Adventive embryony, also called sporophytic apomixis, sporophytic budding, or nucellar embryony: Here there may be a megagametophyte in the ovule, but the embryos do not arise from the cells of the gametophyte, they arise from cells of nucells or the integument. Adventive embryony is important in several species of Citrus, in Garcinia, Euphorbia dulcis, Mangifera indica etc.
(iii) Vegatative apomixis : In this type “the flowers are replaced by bulbils or other vegetative propagules which frequently germinate while still on the plant”.
(iv) Vegatative apomixis is important in Allium, Fragaria, Agave, and some grasses among others.