Why some seeds referred as apomitic …

Apomixis is the asexual production of seeds, so that apomictic seeds are clones of the mother plant. The production of viable seeds without pollination or fertilisation, is called apomixis. These seeds are produced from flowers, just as regular seeds, but no pollen is involved. The underlying mechanism of generating apomictic seeds is that seeds arise from a plant's sexual cells, which fail to go through the cellular mechanism underlying sexual reproduction i.e meiosis. Alternatively, seeds can be generated from non-sexual somatic cells too. The plants grown from such seeds are perfect clones of the original plant. For example, Mangosteen produces apomictic seeds within the fruit. Even dandelion produces many apomictic seeds.
 
Advantage of apomixis is that it would drastically reduce the cost of hybrid production, so that plant breeders produce new varieties of seeds more quickly and more cheaply.
Disadvantage of apomictic seeds, is that it reduces genetic diversity from parent to offspring plants due to lack of variations in asexual reproduction.