Are Pine Nuts Tree Nuts?

While legally classified as tree nuts in the United States, pine nuts are the seeds found inside pine cones. While all are edible, some species of pine nut have a better flavor than others and are used extensively in cooking and as snack food by those who enjoy their slightly bitter taste. Pine nuts are the means by which pine trees, of the genus Pinus, reproduce, and their seeds are often carried far from parent trees by red squirrels, whose diet consists mainly of these seeds.

A nut is the fruit of a nut tree, usually enclosed in a tough outer coating that must be removed. Examples of these are walnuts and pecans. A seed is the reproductive part of a plant, and is essentially its embryonic stage. When flowers are pollinated, their embryos develop an outer coating called an integument. Seeds eventually evolve into fruit, legumes, dry capsules or the caryopsis produced by grasses such as wheat. Nuts, however, do not evolve, as they themselves are the products of whatever tree produced them. Because a pine seed is enclosed by an outer shell, it can be considered both a nut and a seed, particularly from a culinary point of view.

Several species of pine trees produce seeds that are easily harvested and flavorful enough to be eaten. The seeds of the Pinus edulis, New Mexico's state tree, are considered a delicacy there, while the nuts of the Pinus monophylla, the state tree of Nevada, are prized in parts of the southwestern United States. Pine nuts most often used in cooking are the seeds of Pinus pinea, and are native to the Mediterranean region, while Pinus koraiensis seeds are harvested in Korea and China.

Pine nut harvesting is a long process that involves stripping pine trees of their entire crop, from breaking off those still in the trees to gathering those that have fallen to the ground. The cones are then exposed to sunlight or heat for drying and to open the brackets, which makes the job of extracting the seeds easier. Seeds are removed by hand or by machine and then subjected to a second drying before their hard outer shells are removed. Pine nuts are expensive because most of this time-consuming work is done manually.

Shelled pine nuts taste best if they are toasted lightly in a dry skillet, and are one of the main ingredients in a sauce made with basil leaves and garlic, called pesto, that is generally served over pasta. Pine nuts roasted in their shells are also nutritious, though a labor-intensive snack, as they contain heart-healthy monounsaturated fat, and are good sources of vitamins A, C, D and E, as well as protein and fiber.