Evergreen trees, such as the pine, spruce and cedar, are known as conifers in the scientific world. They get the name because they don't reproduce via fruit or flowers, like deciduous trees. Instead, their reproductive cycle takes place inside a pinecone--actually two pinecones, a male and female.
Most people don't know that not all pinecones are created alike. Evergreen trees are asexual, meaning they can self-reproduce. To do this, they need two genders of pinecones. The male pinecone, or staminate cone, is usually smaller than the female, or ovulate, cone. The job of the male cone is to make pollen in its microsporangia, small sacs under each "leaf" of the cone. The female cone has ovules toward the center of its structure, each holding an egg cell.
The male cone distributes pollen to the female via the wind. Depending on the direction the wind blows, it can transfer the pollen to another cone on the same plant or to another evergreen tree nearby. The female cone, which is often closed at this point, giving it a soft, green appearance, collects the pollen and begins the process of meiosis, or cell division, so that it can produce more than one seed from each egg. Most often the "leaves" of the female cone, called "seed scales" end up with two seeds on the base of each scale. The rest of the scale forms a "wing," which helps makes the seeds more aerodynamic.
Once the seeds are fully developed, which in some species can take a year or longer, the female pinecone opens up, beginning to look like the crunchy brown pinecones we're used to finding on the ground. This allows the seeds to fall out and flutter to the ground below or be carried further away by gusts of wind. In some species, a sticky substance, or "pitch," near the base of the cone can attach to animals' fur or feathers as they pass by the tree. This also helps spread the seeds to new areas. Eventually, the entire pinecone will detach from the evergreen tree and fall to the ground.
After the seed hits the forest floor, all it takes is a little water and sun to help the seedling take root. If you've ever been in the woods in an area with a relatively cold climate, you know that evergreen trees tend to be prolific. As the young tree grows, it begins to produce pinecones of its own and the reproductive cycle begins all over again.