Pinus (the true pines) is the largest and most widespread genus, characteristic of many north temperate regions (except the plains), especially at lower altitudes, and in a few tropical regions, notably on mountain slopes. Species of Pinus can often be identified by the leaf arrangement, one needle or clusters of from two to five (in all cases enclosed in a sheath at the base) being consistently produced by each type. Many of the pines are economically valuable; from them come the naval stores: pitch (see tar and pitch), turpentine, and rosin. Drying and nondrying oils are also made from the seeds of some pines. Several Mediterranean and American species yield edible seeds (see pine nut).
The ponderosa pine or western yellow pine (P. ponderosa), is a hard pine second only to the Douglas fir as a commercial timber tree in North America. The white pine (P. strobus) has straight-grained soft wood with little resin, used especially for interior trim and cabinetwork. It once grew densely from Newfoundland to Manitoba and over much of the E United States westward to Minnesota, but constant felling and attacks of white-pine blister rust have greatly depleted the stands, especially in the NE United States. The Norway pine, or red pine, (P. resinosa) has a similar range and has also suffered from overcutting. Its wood is somewhat heavier and is suitable for general construction. The Norway pine is frequently used in reforestation programs. The jack pine (P. banksiana), the most northern of the American species, thrives on poor and sandy soils and is much used to colonize areas where more valuable species may later be introduced. Although the trunk is often gnarled, making it unsuitable for good lumber, it supplies much pulpwood and is used locally for rough lumber, fuel, and crating. The Virginia pine (P. virginiana) of the Appalachians and the Piedmont is popular regionally as a Christmas tree. The longleaf pine, or Southern yellow pine (P. palustris) has highly resinous wood used for heavy construction and as a major source of naval stores and pulpwood. It and the faster growing slash pine (P. caribaea) of the same region have gained importance as northern pine stands have been depleted. The latter is widely cultivated in tropical areas with sandy soils. The Scotch pine (P. sylvestris), ranging from Scotland to Siberia and popular as a Christmas tree in the United States, is one of the most valuable timber trees of Europe. The cluster pine (P. pinaster), widespread in S France and in Spain, is the chief European source of turpentine. The Monterey pine (P. radiata) of California has been widely planted in New Zealand and Chile for reforestation.
Abies (fir) species are usually of more northern distribution and found at higher altitudes. Sap-filled "blisters" on the trunks of some species provide balsam. Larix (larch) and Pseudolarix (golden larch, of China) are the only two deciduous genera. Picea (spruce) is the world's most important source of paper. Cedrus (cedar) ranges from the Mediterranean area to the Himalayas; Keteleeria is restricted to E and SE Asia.
Tsuga (hemlock) and Pseudotsuga are native only to North America and E Asia. Pseudotsuga menziesii (the Douglas fir) of W North America, one of the tallest trees known (up to 385 ft/117 m) and the leading timber-producing tree of the continent, is carefully controlled by forestry measures. Its wood, usually hard and strong, is of great commercial importance for construction; it is also commonly used as a Christmas tree in the United States. Named for David Douglas, the tree has many local names, e.g., Douglas spruce, Oregon pine, red fir, and yellow fir.
Pines are classified in the division Pinophyta, class Pinopsida, order Coniferales.
Cluster of pollen-bearing male cones of Austrian (black) pine (Pinus nigra).
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Any of about 200 species of primitive vascular plants that constitute the genus Lycopodium (order Lycopodiales), mainly native to tropical mountains but also common in northern forests of both hemispheres. They are evergreen plants with needlelike leaves and, often, conelike clusters of small leaves (strobili; see cone), each with a kidney-shaped spore capsule at its base. Representative species include running pine, or stag's horn moss (L. clavatum), ground cedar (L. complanatum ‘flabelliforme'), shining club moss (L. lucidulum), fir club moss (L. selago), ground pine (L. obscurum), and alpine club moss (L. alpinum).
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Norfolk Island pine (Araucaria excelsa).
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Pines are coniferous trees in the genus Pinus, in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.
Pines are native to most of the Northern Hemisphere. In Eurasia, they range from the Canary Islands and Scotland east to the Russian Far East, and the Philippines, north to just over 70°N in Norway (Scots Pine) and eastern Siberia (Siberian Dwarf Pine), and south to northernmost Africa, the Himalaya and Southeast Asia, with one species (Sumatran Pine) just crossing the Equator in Sumatra to 2°S. In North America, they range from 66°N in Canada (Jack Pine) south to 12°N in Nicaragua (Caribbean Pine). The highest diversity in the genus occurs in Mexico and California.
Pines have been introduced in subtropical and temperate portions of the Southern Hemisphere, including Chile, Brazil, South Africa, Australia, and New Zealand, where they are grown widely as a source of timber, and some species are becoming invasive.
The bark of most pines is thick and scaly, but some species have thin, flaking bark. The branches are produced in regular "pseudo whorls", actually a very tight spiral but appearing like a ring of branches arising from the same point. Many pines are uninodal, producing just one such whorl of branches each year, from buds at the tip of the year's new shoot, but others are multinodal, producing two or more whorls of branches per year. The spiral growth of branches, needles and cone scales are arranged in Fibonacci number ratios. The new spring shoots are sometimes called "candles"; they are covered in brown or whitish bud scales and point upward at first, then later turn green and spread outward. These "candles" offer foresters a means to evaluate fertility of the soil and vigour of the trees.
Pines have four types of leaves:
1. Seed leaves (cotyledons) on seedlings, borne in a whorl of 4-24.
2. Juvenile leaves, which follow immediately on seedlings and young plants, 2-6 cm long, single, green or often blue-green, and arranged spirally on the shoot. These are produced for six months to five years, rarely longer (and also produced later in life after injury in some pines).
3. Scale leaves, similar to bud scales, small, brown and non-photosynthetic, and arranged spirally like the juvenile leaves.
4. Needles, the adult leaves, which are green (photosynthetic), bundled in clusters (fascicles) of (1-) 2-5 (-6) needles together, each fascicle produced from a small bud on a dwarf shoot in the axil of a scale leaf. These bud scales often remain on the fascicle as a basal sheath. The needles persist for 1.5-40 years, depending on species. If a shoot is damaged (e.g. eaten by an animal), the needle fascicles just below the damage will generate a bud which can then replace the lost leaves.
Pines are mostly monoecious, having the male and female cones on the same tree, though a few species are sub-dioecious with individuals predominantly, but not wholly, single-sex. The male cones are small, typically 1-5 cm long, and only present for a short period (usually in spring, though autumn in a few pines), falling as soon as they have shed their pollen. The female cones take 1.5-3 years (depending on species) to mature after pollination, with actual fertilization delayed one year. At maturity the female cones are 3-60 cm long. Each cone has numerous spirally arranged scales, with two seeds on each fertile scale; the scales at the base and tip of the cone are small and sterile, without seeds. The seeds are mostly small and winged, and are anemophilous (wind-dispersed), but some are larger and have only a vestigial wing, and are bird-dispersed (see below). At maturity, the cones usually open to release the seeds, but in some of the bird-dispersed species (e.g. Whitebark Pine), the seeds are only released by the bird breaking the cones open. In others, the fire climax pines (e.g. Monterey Pine, Pond Pine), the seeds are stored in closed ("serotinous") cones for many years until a forest fire kills the parent tree; the cones are also opened by the heat and the stored seeds are then released in huge numbers to re-populate the burnt ground.
Pines grow well in acid soils, some also on calcareous soils; most require good soil drainage, preferring sandy soils, but a few, e.g. Lodgepole Pine, will tolerate poorly drained wet soils. A few are able to sprout after forest fires, e.g. Canary Island Pine. Some species of pines, e.g. Bishop Pine, need fire to regenerate and their populations slowly decline under fire suppression regimes. Several species are adapted to extreme conditions imposed by elevation and latitude; see e.g. Siberian Dwarf Pine, Mountain Pine, Whitebark Pine and the bristlecone pines. The pinyon pines and a number of others, notably Turkish Pine, are particularly well adapted to growth in hot, dry semi-desert climates.
The seeds are commonly eaten by birds and squirrels. Some birds, notably the Spotted Nutcracker, Clark's Nutcracker and Pinyon Jay, are of importance in distributing pine seeds to new areas. Pine needles are sometimes eaten by some Lepidoptera (butterfly and moth) species (see list of Lepidoptera that feed on pines) and also the Symphytan species Pine Sawfly.
Pines are among the most commercially important of tree species, valued for their timber and wood pulp throughout the world. In temperate and tropical regions, they are fast-growing softwoods that will grow in relatively dense stands, their acidic decaying needles inhibiting the sprouting of competing hardwoods. Commercial pines are grown in plantations for timber that is denser, more resinous, and therefore more durable than spruce (Picea). Pine wood is widely used in high-value carpentry items such as furniture, window frames, paneling and floors.
Many pine species make attractive ornamental plantings for parks and larger gardens, with a variety of dwarf cultivars being suitable for smaller spaces. Pines are also commercially grown and harvested for Christmas trees. Pine cones, the largest and most durable of all conifer cones are craft favorites. Pines boughs, always appreciated, especially in wintertime for their pleasant smell and greenery, are popularly cut for decorations.
The soft, moist, white inner bark (cambium) found clinging to the woody outer bark is edible and very high in vitamins A and C. It can be eaten raw in slices as a snack or dried and ground up into a powder for use as a thickener in stews, soups, and other foods, such as pine bread. A tea made by steeping young, green pine needles in boiling water (known as "tallstrunt" in Sweden) is high in vitamins A and C.