Conifers represent the next level of plant evolutionary development.
The pine tree with which we are familiar is the sporophyte. Meiosis also results in the production of four megaspores, three of which die, leaving a single functional megaspore. Within a pollen grain lies two cells, a generative sperm cell and a tube cell . Pollination occurs when the pollen grain penetrates the micropyle of the female scale. The tube cell elongates into a pollen tube that, over a period of a year or more, eventually reaches the egg cell.