Pines belong to a group of plants called conifers. All conifers reproduce by means of cones that produce pollen and seeds. A pine differs from other conifers in the way its leaves grow. Nearly all pines have needles that grow in bundles of two, three, or five each. The leaves of other conifers grow in larger bundles or do not form bundles.
Conifers closely related to pines include firs, larches, and spruces.
Pine trees bear both male and female cones. The female cones are much larger and have woody scales. In the spring, the male cones produce enormous quantities of pollen. The wind carries the pollen to egg cells attached to the scales of the female cones. The pollen fertilizes the egg cells, which then develop into seeds.