The power of life is inherent within a pine tree, which can contain male and female sexual reproductive structures within the same tree. Pine trees are gymnosperms, a plant species that reproduce via "naked seeds," or seeds not enclosed in an ovary. This method of reproduction replaces the pollination reproduction method of flowering plants, or angiosperms. Pine trees are native to North America, Europe and Southeast Asia.
The life cycle of a pine tree begins in the strobulus, the sexual reproductive structure in a fully mature pine tree. Strobulii are also known as the "pine cones." Male strobulii are in the lower part of the tree, while the female structures are in the upper part. The strobulli are considered unisexual structures, because they host either male or female sexual organs. The male strobulli in a pine tree contain microsporocytes, grains that eventually develop into pollen. In the spring months, male strobulli release pollen into the air, which is aimed for the pine tree's female strobulli.
Once pollen is released into the air, some of the grains will land in female pine cones. This initiates the stage of pollination. When the pollen lands in the strobilus, it eventually makes its way to the plant's nucellus. This transforms the pollen grain into a pollen tube. As a result, the female strobilus creates four megaspores, which contain chromosomes. Out of the four megaspores, one will survive and become a megagametophyte. The pollination stage of pine tree life lasts for approximately one year, until the megagametophyte develops egg cells.
In fertilization, the egg cells of the megagametophyte come into contact with the pollen tube. When this happens, the pollen tube inserts two nuclei into the egg cells; the nuclei act as sperm. One of the nuclei will join with the the nucleus within the egg. This union forms a zygote. Eventually the zygote will develop into a seed, which contains an embryo. The seed is dispersed from the female strobilus via the wind or wildlife species, such as birds or insects.
After they are dispersed from the parent tree, the pine seeds land on the earth and commence the growth process. In general, pine tree species need full sunlight for maximum growth. Pine trees prefer acidic or sandy soils. However, they are able to grow in environments that are difficult for other trees, such as rocky sites, limestone and habitats at high altitudes. Pine trees can grow up to 150 feet and have a lifespan of over 100 years.