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Polyembryony is the phenomenon of development of more than one embryos in a seed. It was discovered by Leeuwenhock in 1719 in orange. It may be of two types—
I. True : When embroys arise in the same embryosac in which zygotic embryo has developed.
II. False : When extra embryos are developing in one embryosac other than the one in which zygotic embryo is developed.
More than one embryo may be developed in the seed by one of the following methods:
1. Cleavage polyembryony : When more than one embryos are formed by cleavage or splitting of normal zygote. e.g., Erythronium americanum, Nymphea advena, Nicotiana rustica.
2. Embryo from synergid : Synerged is fertilized by sperm e.g., Saggitaria,
3. Embryo from antipodal : e.g., Ulmus americana.
4. Embryo from endosperm : e.g., Balanophora.
5. Adventive embryony : (Embryo formed from cells of nucellus which penetrate into embryo sac. Eugenia, Mangifera,
6. Embryo originating from other embryosac in the ovule : e.g., Citrus.