Pollen grains of many species cause severe allergies.

Stored pollen in liquid nitrogen can be used in the crop breeding programmes.

Tapetum helps in the dehiscence of anther.

Exine of pollen grains is made up of sporopollenin.

free nuclear proembryo

free nuclear endosperm

endocarp

fleshy mesocarp.

Pollen germination and pollen tube growth are regulated by chemical componrnts of pollen interacting with those of the pistil.

Some reptiles have also been reported as pollinators in some plant species.

Pollen grains of many species can germinate on the stigma of a flower, but only one pollen tube of the same species grows into the style.

Insects that consume pollen or nectar without bringing about pollination are called pollen/ nectar robbers.

involve meiosis

occur in ovule

occur in anther

form gametes without further divisions.