The reproductive whorls
The inner two whorls. These are the reproductive structures — everything outside them exists to serve what happens here.
3. Androecium (stamen)
The male reproductive structure of a flower is the androecium. It consists of two parts, the anther and the filament.
Inside the anther are the pollen sacs, and within them lies the pollen. When mature, the anthers burst open and the pollen comes out.
The pollen is what acts as the male reproductive cell in plants.
4. Gynoecium
The female reproductive structure of a flower is the gynoecium. It consists of three parts — the stigma, the style and the ovary.
The ovules are situated within the ovary.
The ovule is what acts as the female reproductive cell in flowers.
Three parts, one route
Read the gynoecium from the top down and it is a path: the stigma is where pollen lands, the style is what it travels through, and the ovary is where it arrives. Knowing that, the whole of fertilisation two sections from now is already half understood.