Advantages of modern methods
(i) Plants with desired characteristics can be multiplied rapidly in a short duration.
(ii) Plants produced are genetically identical.
(iii) Tissue culture can be carried out in any season.
(iv) Plants which do not produce viable seeds and seeds that are difficult to germinate can be propagated. 
(v) Rare and endangered plants can be propagated. Disease-free plants can be produced cells can be genetically modified and transformed.

Pollination by bees is called mellitophily.

A diploid embryosac is formed from megaspore mother cell without a regular meiotic division
Example:
Eupatorium, Aerva

The endosperm in gymnosperms is haploid because it is formed from the haploid megaspore. In angiosperm the endosperm is triploid, a product or triple fusion.

Dichogamy stamens and stigmas mature at different times (protandry, Protogyny) Herkogamy - Stamens and stigmas are arranged in such a way, self pollination become impossible.

Pollination carried out by beetle is called cantharophily.

Supplies nutrition to the developing microspores contributes sporopollenin through, ubisch bodies. This plays an important role in pollen wall formation. The pollen kit material is contributed by tapetal cells, and is later, transferred to the pollen surface. Exine protein responsible for rejection reaction are derived from tapetal cells.

Endothecium is a single layer of radially elongated cells, The inner tangential wall of this cell develops bands of a cellulose, The cells are hygroscopic. The stomium of anther lobe lack these thickenings. Stomium along with the hygroscopic nature of endothecium helps in the dehiscence of anther

The primary endosperm nucleus divides immediately after fertilization. It develops into an endosperm which is a nutritive tissue and a regulatory structure. The zygote divides only after that to form an embryo so that it can get nourishment from the endosperm that has formed earlier.

In some species (unitegmic, tenuinucellate) the inner layer of integument becomes specialized, The layer is nutritive in function for the embryosac. This layer is called endothelium or integumentary tapetum.
Example:
Asteraceae.