Native to the woodlands of the southeastern United States, both loblobby pine (Pinus taeda) and shortleaf pine (Pinus echinata) can mature to heights over 100 feet and tend to drop their lowermost branches to reveal a barren trunk. To the untrained eye, it's difficult to distinguish these two species; even more challenging is the fact, according to The Gymnosperm Database, that both pines readily hybridize with each other where they grow in the same areas. Thus, these hybrid seedlings muddy the distinguishing features, but tend to look more like shortleaf pines than loblolly pines.
Historically, the natural growing range of both these trees was in a large band across the American Southeast. According to The Gymnosperm Database, European settlement and changing land use across the region caused a change in the typical soils in which each tree was found growing. Loblolly pine's native range extends from Delaware south to central Florida in the Piedmont and coastal plain and then westward to eastern Texas. Shortleaf pine's range is similar, except that it also grows in the higher elevations of the Appalachians as well as around the Tennessee River, Ozark highlands and westward to eastern Texas. Neither pine species is native to the lowland delta elevations in the lower Mississippi River valley.
With age, the tall, straight trunks of both pines are nearly nude of lower branches, perhaps a few dead short branches in the middle to upper reaches of the trees just below the living foliage. While there can be variability in each tree based on the location's soil, rainfall and wind, the shape of the pine top's canopy can provide insight into its identity. The loblolly pine's canopy is rather open in shape but has an oval outline. In contrast, the shortleaf pine's open canopy at the top of the trunk is a bit more jagged and irregular, perhaps looking like a pyramid, according to the plant database of Virginia Tech University.
The clusters of needles on pine trees are known as fascicles. The loblolly pine's fascicles comprise three needles per fascicle and each needle measures between 6 and 9 inches in length. The deep yellow-green leaves slightly twist and remain on the tree for three years before dying and being shed to the ground. Overall, more litter is produced by a loblolly pine than a shortleaf pine. The shortleaf pine's fascicle also consists of two or three needles, but they are only 3 to 5 inches long. They are gray to yellow-green, slightly twisted and persist on the branches for three to five years before dropping away.
Shortleaf pine trees produce female (woody) cones that are red-brown and slowly mature to gray over the course of two to three years as they persist on the branches. The many cones, each measuring about 2 inches, are held in small clusters. The scales in the cones remain somewhat flexible. Loblolly pine cones are more yellow-brown in color and ripen in two years and readily drop from the tree in the second year. The more rigid, stiff cones, when mature and open, are about twice as large as the cones from the shortleaf pine. Both pine species' cones have cone scales with a tiny prinkle on the end.
Loblolly tree bark is grayish red-brown and scaly, and when trees get older the bark is more ridged and furrowed; very tall (old) loblollies have bark with flat, scaly plates that are red-brown. Shortleaf pine tree bark is scaly and a darker brown. The scaly plates that develop have a tan and red-brown hue but are surrounded by dark brown furrows. Tiny resin pockets (pits) can be seen on the bark, and are sometimes described as "volcanoes" according to Virginia Tech University.