Pines evolved in the Northern Hemisphere, with most species naturally occurring between 20 and 70° latitude. The largest genus of conifers contains over 100 species, which may be divided into two or three subgenera. Some say the “hard pines” (subgenus Pinus) contain 64 species while “soft pines” (subgenus Strobus) contain 37 species. Members of the subgenus Pinus have two flbrovascular bundles per needle while the subgenus Strobus only has one.

Pine wood is composed of cellulose, hemicellulose, lignin, oleoresin, uronic anhydride, acetyl and ash. Cellulose, lignin and hemicellulose typically comprise more than 90% of the wood while resins may make up 9% of the oven-dry weight. On an equal mass basis, the economic value of the resins is generally higher than that for wood. The chemical structures and amounts can vary by species because of genetics involved in producing the cell wall and its components.