HORTICULTURE

Detailed explanation-1: -A pollen grain on the stigma grows a tiny tube, all the way down the style to the ovary. This pollen tube carries a male gamete to meet a female gamete in an ovule.

Detailed explanation-2: -As the generative cell moves down the pollen tube, a callus plug is formed to close it behind the generative cell. Once fertilization occurs, the pollen tube collapses and becomes non-functional.

Detailed explanation-3: -The pollen tube invades the pistil, growing between the walls of the stigmatic cells, then traveling through an extracellular matrix within the transmitting tissue of the style. The pollen tube finally arrives at the ovary, where it is attracted to an ovule that contains an egg cell.

Detailed explanation-4: -Sperm cells within the pollen grain move down the pollen tube and into an ovule. Fertilization occurs as one of the sperm cells fuses with the egg inside the ovule. After fertilization takes place, the ovule develops into a seed that contains a tiny, undeveloped plant.