Conifers are one type of nonflowering plant. Within the family of conifer plants are the pines. Pine nuts are the seeds that some species of the genus Pinus (pine trees) use to reproduce. The pine tree will grow both male and female cones. The female cone takes 2 to 3 years to mature, going from a green cone to a woody, brown cone. The male cone gives off pollen, and the female cone catches the pollen. The pollen and the megaspore combine to create a cell which grows into a zygote. The zygote is the baby conifer which lives inside the seed, the pine nut. The mature pine nut contains the embryo of the pine tree, a supply of nutrients and a protective seed coat.
About 29 species of Pinus produce pine nuts. They are produced on both hard and soft pine trees in Europe, North America and Asia. The largest number of pine nuts grow in North America. Of these, the pinon pines are the largest producer of pine nuts. This edible seed grows between the scales of the pine cones found on these pine trees. Two seeds usually grow under each scale. In some species, such as the jack pine, heat (from fire or summer temperatures) is required to make the female cone open her scales, after which her seeds continue to grow. Generally, the pine tree releases seeds in the autumn when the cone has opened more and dried.
Each cone contains as many as 200 pine nuts, each of which has the potential to grow from a seed to a tree. Once a pine seed has fallen from the pine cone, if the conditions are favorable, the pine nut within its seed coat germinates. The embryo consumes the stored nutrients, bursts through the softened seed coat and becomes a sapling. The sapling grows into a tree and around 10 years later begins to produce its own seeds from which pine nuts can be harvested.