Despite a common misconception, all trees with needles are not pine trees. According to Don Janssen of University of Nebraska-Lincoln Extension, the easiest way to determine if a needled tree is a pine is to look at the needles. If they come in clumps, usually of two to five needles, the tree is probably a pine. The length of the needles varies and pine trees are evergreen, meaning that they retain their needles through the winter into the next growing season.
Longleaf pine (Pinus palustris) grows to 60 feet and is found along the southeastern U.S. coast from Virginia to Florida. This pine, which is hardy to 5 degrees Fahrenheit, is oblong in shape and has needles that come in groups of three. The longleaf pine produces dull brown cones up to 10 inches long. These trees are slow growers in the first 10 years and resemble fountains of grass before taking shape.
Monterey pine (Pinus radiata) is prevalent along the central California coast and grows to 100 feet. Hardy to 15 degrees Fahrenheit, the Monterey pine is a towering tree that is round and well-balanced. This tree has needles in groups of two or three and produces 6-inch light brown cones in clusters. A fast-growing tree, the Monterey pine can grow 6 feet per year, but is shallow-rooted and may be blown down by strong winds.
A popular Christmas tree, the Scotch pine (Pinus sylvestris) is hardy in zones 3 through 8a. Scotch pines can grow to 100 feet and blue-green needles are in clusters of two. These trees produce small, gray to reddish brown cones and, when mature, have red bark. As the Scotch pine ages, its shape changes from conical to irregular with drooping branches.