Answer:
Replacement of the normal sexual
reproduction 'by asexual reproduction without fertilization is called apomixis.
e.g., replacement of the flower by bulbils and replacementof the seed by a
plant.Apomitically produced offsprings are genetically identical to the parent
plant. In floweringplants, apomixis is used in a restricted sense to mean
angiosperm, i.e., asexualreproduction through seeds.In some plant species it is
common, e.g., Asteraceae,Poaceae. In some species,
thediploid egg cell is formed without reduction division and develops into
embryo withoutfertilization. It is an asexual reproduction in the absence of
pollinators such as in extremeenvironments.
In some species like citrus, some of the
nucellar cells surrounding the embryo sac startdividing and develop into
embryo. It occurs in the megaspore mother cell does not undergomeiosis, thus
produces diploid embryo sac through mitotic divisions.
Thus, it explains that, embryo sacs of
some apomictic species appear normal, but producediploid cells.
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