Sexual Reproduction in Flowering Plants

Apomixis is the formation of seeds without fertilisation.
In many $Citrus$ and mango varieties some of the nucellar cells surrounding the embryo sac start dividing, protrude into the embryo sac and develop into embryos.
The nucellus is diploid maternal sporophytic tissue of the ovule, so these embryos are genetically identical to the mother plant (adventive embryony).
In such species each ovule contains many embryos (polyembryony).
Hence apomictic embryos in citrus arise from maternal sporophytic tissue in the ovule.