Write short notes on the following:
(a) How pollination occurs in Zostera?
(b) Write floral rewards for insect pollination
(c) Double fertilisation

(a) In Zostera, female flowers remain submerged in water and the pollen grains are released inside the water. Pollen grains are long, ribbon like and they are carried passively inside the water; some of them reach the stigma and achieve pollination. In most of the water-pollinated species, pollen grains are protected from wetting by a mucilaginous covering.
(b) To sustain animal visits, the flowers have to provide rewards to the animals. Nectar and pollen grains are the usual floral rewards.

(c) Double fertilsation is the unique characteristics of angiosperms. During double fertilisation, one male gamete fuses with the egg cell (Syngamy) to for the diploid zygote and one male gamete fuses with the two polar nuclei to form the triploid primary endosperm nucleus. This is called triple fusion. Syngamy and triple fuion together is called double fertilisation.