A) apospory
B) apomixis
C) diplospory
D) adventive polyembryony
Correct Answer: A
Solution :
Formation of diploid embryosac from diploid vegetative structure (nucellus or integument) without meiosis is called apospory. In aposporous plants a normal megaspore mother cell differentiates, undergo meiosis and form tetrad. During this period one or more adjacent nucellur cells become meristematic and undergo mitotic division to form diploid embryo sac eg, Permisetum, Hieracium etc. Apomixis is the formation of embryo without interupting meiosis and syngamy. Such asexual seeds which produce progeny identical to female parent are called apomictic seeds. When the megaspore mother, cell differentiates as in sexual ovule but does not enter in meiosis and produce diploid embryosac through meiosis it is called diplospory, eg, Taraxacum Ixeris, Antennaria etc. When the embryo arises from the maternal sporophytic tissue (outside the embryosac ie, nucellus and integuments) it is called adventive embryo and such polyembryony as adventitive polyembryony e.g., Citrus.
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