Pine Trees: Species, Characteristics & Economic Importance

Pine

Introduction to Pine

Pine, an evergreen tree of great economic importance. Pines are conifers (cone-bearing trees) related to firs, cedars, larches, hemlocks, and araucarias. Pines make up the genus Pinus of the family Pinaceae. There are more than 90 recognized species, all native to the Northern Hemisphere. Most pines are found in areas with a temperate climate, but a few grow in mountainous tropical regions. About 30 species are native to the United States.

General Description and Importance

Most pines have straight, tapering, undivided trunks, with rounded or pyramid-shaped crowns composed of many branches arranged in tiers, or whorls. Pines that cling to wind-swept dunes or cliffs may be stunted and twisted, with few branches. Some kinds of pines may attain a height of more than 200 feet (60 m), with trunks up to 12 feet (3.7 m) in diameter.

Each pine tree has two kinds of leaves—primary and secondary. The secondary leaves, or needles, grow in bundles called fascicles from the axil (the area between the leaf and stem) of the primary leaves. The primary leaves, which are barely visible, form a papery sheath at the base of each fascicle.

Each tree also has two kinds of reproductive organs: (1) pollen cones; and (2) seed cones. The pollen cones grow in clusters at the ends of mature branches, and may be yellow, orange, red, or purple. The immature seed cones, usually pale green, grow singly, paired, or in groups near the ends of young shoots. They mature in two or three years, growing woody and darkening to brown or purple. In some species, the seed cones open at maturity to release their seeds; in others they remain closed for several years. A seed usually has one or two wings.

The number of needles in a fascicle, the length of the needles, and the size and shape of the seed cones vary according to the species. Needles are from 1 to 18 inches (2.5 to 45 cm) long, and usually there are two to five in a fascicle. Seed cones are from 1 inch (2.5 cm) to more than 20 inches (50 cm) long, and may be slender, globe-shaped, or flattish. In some species, the scales of the seed cones have barbs on them. The term cone as used in the rest of this article refers only to the seed cone.

Pines are useful to humans not only for their timber, but for resins and oils from which turpentine, tars, insecticides, and medicines are made. Fast-growing species are used in reforestation programs. Pines are often cultivated for shade and as ornamentals. For a description of the woods of important pines and their uses, table Widely Used American Softwoods.

Traditionally, all conifers are known as softwoods, as distinguished from such broad-leaved trees as oaks and maples, which are called hardwoods. However, for commercial purposes in the United States and Canada, pines are classed as soft pines and hard pines.

American Soft Pines

Soft pines have close-grained, lightweight wood, pale in color. It is not highly resinous, and is easily worked, but may be brittle. Most soft pines have five-needled fascicles. At maturity (5 to 10 years), the sheaths and fasciles are shed. The cones are usually not barbed.

True White Pines

are important timber trees. They have five-needled fascicles, and the blue-green needles are usually marked with white lines that give the foliage a frosted appearance. White pines include:

Eastern White Pine,

the largest conifer native to eastern North America, often reaching a height of 120 feet (37 m) or more. It has needles 3 to 5 inches (7.5 to 12.5 cm) long, and cones 4 to 8 inches (10 to 20 cm) long. This tree grows from Newfoundland south to Georgia, and west through the Great Lakes region to Manitoba and Minnesota. It is the state tree of Maine and of Michigan.

The eastern white pine is Pinus strobus.

Western White Pine,

one of the world's largest pines, sometimes reaching a height of 200 feet (60 m). Its needles are 2 to 4 inches (5 to 10 cm) long, and its cones 6 to 12 inches (15 to 30 cm) long. The tree is native to the Rocky Mountains and the Pacific Coast from British Columbia to northern California. It is the state tree of Idaho.

The western white pine is P. monticola.

Sugar Pine,

largest of all pines, sometimes reaching a height of 220 feet (67 m). Its stiff needles are 3 to 4 inches (7.5 to 10 cm) long, and its cones are 10 to 24 inches (25 to 60 cm) long. Its sap contains a sugary substance. The tree grows in the mountainous coastal regions from Oregon to Lower California.

The sugar pine is P. lambertiana.

Stone Pines

are named for their large, hard-shelled seeds, which are either short-winged or wingless. The trees are 20 to 60 feet (6 to 18 m) tall. The needles are 2 1/2 to 3 1/2 inches (6.5 to 9 cm) long. Species include the limber pine of the Rocky Mountains from Canada to Mexico, and the whitebark pine, found from Alberta and British Columbia to central California. The limber pine bears cones 3 to 10 inches (7.5 to 25 cm) long. The whitebark's cones are 1 1/2 to 3 inches (4 to 7.5 cm) long.

The limber pine is P. flexilis; the whitebark, P. albicaulis.

Piñons (also Spelled Pinyons), or Nut Pines,

are named from the Spanish word for pine nut. The edible seeds of some piñons are widely distributed commercially. Piñons have stiff, curved needles 1 to 1 1/2 inches (2.5 to 4 cm) long, and rounded cones 1 to 2 inches (2.5 to 5 cm) in diameter. They grow in mountainous and in arid regions from Idaho and Colorado to Mexico. The Mexican piñon and the two-leaved (or Colorado) piñon usually have two-needled fascicles. The trees are 20 to 60 feet (6 to 18 m) tall. The two-leaved piñon is the state tree of New Mexico. The single-leaf piñon has one needle to a fascicle, and is 15 to 50 feet (4.6 to 15 m) tall. It grows from Utah to Lower California, and is the state tree of Nevada.

The Mexican piñon is P. cembroides; the two-leaved, P. edulis; the single-leaf, P. monophylla.

Foxtail Pines

are named for the bushy tufts of needles that grow at the ends of naked branches. The dark-green needles are 1 to 1 1/2 inches (2.5 to 4 cm) long. The barbed cones are 3 to 5 inches (7.5 to 12.5 cm) long. Foxtail pines grow to about 40 feet (12 m) tall. One species is limited to California. Two other species are scattered through mountainous areas in the West: the Rocky Mountain bristlecone pine in Colorado, New Mexico, and Arizona and the intermountain bristlecone pine in California, Nevada, and Utah. Bristlecone pines can live more than 4,500 years and are among the oldest living organisms known.

The California foxtail pine is P. balfouriana; the Rocky Mountain bristlecone, P. aristata; the intermountain bristlecone, P. longaeva.

American Hard Pines

Hard pines are also called yellow pines, or pitch pines. Their wood is heavy, dark, resinous, and usually strong and durable. There are usually two or three needles to a fascicle. Most hard pines have barbed cones.

Three-needled Hard Pines

are found mostly in western North America. They include:

Ponderosa, or Western Yellow, Pine,

the most important timber pine in the West. The tree may reach a height of 200 feet (60 m). Its yellow-green needles are 4 to 10 inches (10 to 25 cm) long, and its cones are 3 to 6 inches (7.5 to 15 cm) long. It is widely distributed from British Columbia to Mexico, occurring in every state west of the Great Plains. It is the state tree of Montana.

The ponderosa pine is P. ponderosa.

Monterey Pine,

a tree often cultivated for the beauty of its brilliant, deep-green foliage. It is 50 to 100 feet (15 to 30 m) in height. A few varieties are two-needled. The needles are 3 1/2 to 6 inches (9 to 15 cm) long, and the cones 2 to 5 inches (5 to 12.5 cm) long. This pine is native to central California only, but has been introduced into other parts of the United States, and is cultivated in Europe, Australia, and New Zealand.

The Monterey pine is P. radiata.

Slash Pine,

an important timber tree of the South. It also yields resin of high quality for making turpentine. It is 80 to 100 feet (24 to 30 m) tall. The dark-green needles are 8 to 12 inches (20 to 30 cm) long, and the cones are 3 to 6 inches (7.5 to 15 cm) long. Slash pines often grow in slashes—open areas created by logging or forest fires. The tree is found from eastern Louisiana eastward to Florida and the West Indies, and in Central America. It is the state tree of Alabama, where it is called Southern pine.

The slash pine is P. elliottii.

Longleaf Pine,

also an important Southern timber tree and source of turpentine. It is 80 to 100 feet (24 to 30 m) tall. Its dark-green needles are 8 to 18 inches (20 to 45 cm) long, and its cones are 5 to 10 inches (12.5 to 25 cm) long. It is found on coastal plains from Virginia to Florida, and west to Texas. Its wood is heavy and tough, and yellowish in color.

The longleaf pine is P. palustris.

Loblolly Pine, or Old-field Pine,

an important timber tree and a major source of wood pulp and paper products. The tree is about 100 feet (30 m) tall, with stiff, twisted, pale-green needles 5 to 9 inches (12.5 to 22.5 cm) long. Its cones are 3 to 6 inches (7.5 to 15 cm) long. It grows on coastal plains—often in moist areas called loblollies —from New Jersey to Florida, and west to Texas.

The loblolly pine is P. taeda.

Pitch Pine,

a common name given to all hard pines, but to two species in particular: (1) an eastern pine found from Maine to Georgia; and (2) a California pine, also called Coulter pine. The eastern pitch pine is 50 to 60 feet (15 to 18 m) tall, with yellow-green needles 3 to 5 inches (7.5 to 12.5 cm) long, and cones 1 to 1 1/2 inches (2.5 to 4 cm) long. The Coulter pine is about the same height, with blue-green needles 6 to 12 inches (15 to 30 cm) long, and cones 10 to 14 inches (25 to 35 cm) long. Coulter pine seeds are edible.

The eastern pitch pine is P. rigida; the Coulter, P. coulteri.

Two-needled Hard Pines

are found mostly in eastern North America. They include:

Red Pine, or Norway Pine,

a tree valued for its timber and as an ornamental. Its straight reddish-brown trunk is 70 to 100 feet (21 to 30 m) high. It has dark-green needles 5 to 6 inches (12.5 to 15 cm) long. Its 2-inch (5-cm) cones are not barbed. This pine grows from southeastern Canada to Pennsylvania, and through the Great Lakes region to Minnesota. It is the state tree of Minnesota.

The red pine is P. resinosa.

Shortleaf Pine, or Southern Yellow Pine,

another important timber and ornamental tree. It is 80 to 100 feet (24 to 30 m) tall, with dark blue-green needles 3 to 5 inches (7.5 to 12.5 cm) long, and cones 1 1/2 to 2 1/2 inches (4 to 6.5 cm) long. It is found in a wide belt from Long Island south and west to Oklahoma and Texas. It is the state tree of Arkansas.

The shortleaf pine is P. echinata.

Lodgepole Pine,

a western pine 70 to 150 feet (21 to 45 m) tall. In dense forests its trunk grows straight and tapering; it was once used by Indians to support their tepees or lodges. In far northern or rocky coastal regions, it is stunted and twisted, and is sometimes called scrub pine. This pine has yellow-green needles 1 to 3 inches (2.5 to 7.5 cm) long, and cones 1 to 2 inches (2.5 to 5 cm) long. It grows in Pacific coastal regions and the Rocky Mountains from Alaska to Lower California.

The lodgepole pine is P. contorta.

Old World Pines

Pines are found in the Eastern Hemisphere from the Arctic Circle to northern Africa. Several Old World species are cultivated in America.

Scotch Pine, or Scots Pine,

one of the most valuable of Eurasian trees. It is a source of durable timber, and of oils and resins. In its extreme northern range it is small, but farther south it attains heights of 100 to 150 feet (30 to 45 m). The tree grows from Norway south to Spain and northern Italy, and from the British Isles east to Russia's Kamchatka peninsula. The Scotch pine is cultivated in the United States for both reforestation and ornamental purposes.

The Scotch pine is P. sylvestris.

Cluster Pine,

an important timber tree in the Mediterranean. It reaches a height of 100 feet (30 m) or more. The cluster pine is the most important European source of turpentine. It is planted for reforestation purposes, and on sandy shores as a binder of shifting dunes.

The cluster pine is P. pinaster.

Stone Pines

include the Italian stone pine and the Swiss stone pine. Stone pines reach a height of 80 feet (24 m). They are cultivated for their edible seeds and as ornamentals. The Italian stone pine is native to Mediterranean regions of Europe and Africa. The Swiss stone pine is found in the mountains of central Europe and of Siberia.

The Italian stone pine is P. pinea; the Swiss, P. cembra.

Enemies of Pines

Fire is a serious menace because pine wood is resinous. Sawflies, weevils, pine bark beetles, root rot, and tip moths damage pine forests. White pine blister rust, caused by a fungus, destroys the five-needled pines. This rust heavily attacks the white pines of North America.