The shortleaf pine or Pinus echinata is a species of coniferous tree endemic to the United States. The shortleaf pine is sometimes referred to as the "old field", "spruce", "rosemary", "yellow", "two-leaf" and "heart" pine. The common name "shortleaf pine" may refer to other species like loblolly pine, based on a custom in the Southeastern United States to only refer to pines as either "long-leaf" or "short-leaf". However, P. echinata can be distinguished from other pines by examining its short leaves and small cones.

Pinus taeda, commonly known as loblolly pine, is one of several pines native to the Southeastern United States, from East Texas to Florida, and north to southern New Jersey. The wood industry classifies the species as a southern yellow pine. U.S. Forest Service surveys found that loblolly pine is the second-most common species of tree in the United States, after red maple. For its timber, the pine species is regarded as the most commercially important tree in the Southeastern U.S. The common name loblolly is given because the pine species is found mostly in lowlands and swampy areas.