Self-pollination:

(i) Self-pollination occurs within a flowers of between two flowers of the same plants.

(ii) Flowers do not depend on other agencies for pollination.

(iii) Pollen grains are produced in small numbers.

(iv) No wastages of pollen grains occurs and thus, economical.

(v) Flowers are not attractive nor do they produce nectar.

(vi) The offsprings produced are of the same genetic make up, so purity of the race is maintained.

cross-pollination:

(i) Cross-pollination occurs between two flowers borne on different plants of the same species.

(ii) Agents such as insects, water and wind are required for pollination.

(iii) Pollen grains are produced in large numbers.

(iv) Wastage of pollen grains occurs and hence, not economical.

(v) Flowers attract insects by various means like coloured petals, scent and nectar.

(vi) The offsprings produced may show variations and differ in genetic make up.

During fertilisation in plants, the following events take place:

(i) One of the male gamete fuses with the female gamete present in the embryo sac.

(ii) The other male gamete fuses with the two polar nuclei in the embryo sac.

The first fusion product gives rise to the zygote while the second one forms the endosperm. The process of two fusions occurring in the embryo sac is called double fertilisation.