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Pine

From Academic Kids

This article deals with the tree; for the e-mail client see Pine (email client)
Pines
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Maritime Pine (Pinus pinaster)
Scientific classification
Kingdom:Plantae
Division:Pinophyta
Class:Pinopsida
Order:Pinales
Family:Pinaceae
Genus:Pinus
Species

About 115.

Pines are coniferous trees of the genus Pinus, in the family Pinaceae. There are about 115 species of pine, although different authors accept anything from 105 to 125 species.

Contents

Distribution

Pines are native to most of the Northern Hemisphere. In North America, they range from the Arctic south to Nicaragua and Hispaniola, with the highest diversity in Mexico and California. In Eurasia, they range from Portugal and Scotland east to the Russian Far East, Japan, and the Philippines, and south to northernmost Africa, the Himalaya and Southeast Asia, with one species (Sumatran Pine) just crossing the Equator in Sumatra. Pines are also extensively planted in many parts of the Southern Hemisphere.

Morphology

Pines are evergreen and resinous. The bark of most pines is thick and scaly, but some species have thin, flaking bark. The branches are produced in regular "pseudowhorls", 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 light-colored and point upward at first, later darken and spreading outward. These "candles" offer foresters a means to evaluate fertility of the soil and/or vigour of the trees.

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Juvenile (left) and adult foliage of Stone Pine (Pinus pinea); note dark brown scale leaves as well as needles on adult shoot

Foliage

Pines have four types of leaves. Seedlings begin with (1) a whorl of 4-20 seed leaves (cotyledons), followed immediately by (2) juvenile leaves on young plants, 2-6 cm long, single, green or often blue-green, and arranged spirally on the shoot. These are replaced after six months to five years by (3) scale leaves, similar to bud scales, small, brown and non-photosynthetic, and arranged like the juvenile leaves; and (4) the adult leaves or needles, 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 growth.

Cones

 (Pinus taeda): male cones
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Loblolly Pine (Pinus taeda): male cones

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 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, the seeds are stored in closed cones for many years until a forest fire kills the parent tree; the stored seeds are then released in huge numbers to re-populate the burnt ground.

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Young spring growth ("candles") on a Loblolly Pine

Ecology

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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 where they can grow. Pine needles are sometimes eaten by some Lepidoptera species including Pine Processionary, Bordered White (also known as Pine Looper), Pine Beauty and Scalloped Hazel, and also the Symphytan species Pine Sawfly.

Classification of Pines

Pines are divided into three subgenera, based on cone, seed and leaf characters:

  • Subgenus Strobus (white or soft pines). Cone scale without a sealing band. Umbo terminal. Seedwings adnate. One fibrovascular bundle per leaf.
  • Subgenus Ducampopinus (pinyon, lacebark and bristlecone pines). Cone scale without a sealing band. Umbo dorsal. Seedwings articulate. One fibrovascular bundle per leaf.
  • Subgenus Pinus (yellow or hard pines). Cone scale with a sealing band. Umbo dorsal. Seedwings articulate. Two fibrovascular bundles per leaf.

For more details, see Pinus classification (under construction).

List of pines by region

Old World

European & Mediterranean pine species (some extend into Asia)
Asian pine species

New World

Canada & USA, except for close to the Mexican border
Southern Arizona & New Mexico, Mexico, Central America & Caribbean

Name origins

The modern English name pine derives from Latin Pinus by way of French pin. In the past (pre-19th century) they were often known as fir, from Old Norse fyrre, by way of Middle English firre. The Old Norse name is still used for pines in some modern north European languages: in Danish, fyr, in Nowegian, furu, and Fhre in parts of Germany, but in modern English, "fir" is now restricted to Abies and Pseudotsuga. Other unrelated European names include German Kiefer (the most widely used name in Germany), Swedish tall, Dutch den, Finnish mnty, Russian sosna, Bulgarian and Serbo-Croat bor, and Greek pitys. In Chinese it is song, in Japanese matsu, and in Korean it is Sonamu. In Hebrew it is "oren".

Uses

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Commercial planting of young Longleaf Pine (Pinus palustris)

Pines are commercially among the most important of species used for timber in temperate and tropical regions of the world. Many are grown as a source of wood pulp for paper manufacture. This is because they are fast-growing softwoods that can be planted in relatively dense stands, and because their acidic decaying needles may inhibit the growth of other competing plants in the cropping areas. A typical example is Pinus radiata. The resin of some species is important as the source of turpentine. Some species have large seeds, called pine nuts, that are harvested and sold for cooking and baking. Some pines are used for christmas trees, and pine cones are also widely used for christmas decorations. Many pines are also very attractive ornamental trees planted in parks and large gardens. A large number of dwarf cultivars have been selected, suitable for planting in smaller gardens.

Pine plantations can be at risk of fire damage because pine resin is flammable to the point of a tree being explosive under some conditions.

Pines are well-known survival food plants. The soft, moist, white inner bark, or cambium, found clinging to the dead, woody outer bark is edible and very high in vitamins A and C. It can be eaten in slices raw as a snack or dried and ground up into a powder for use as a thickener/flavoring in stews, soups, and other foods. The bunches of young green cones found at the ends of branches make a tasty, healthy hiking snack. A tea made by steeping young, green pine needles in boiling water is delicious and high in vitamins A and C.

References

  • Richardson, D. M. (ed.). 1998. Ecology and Biogeography of Pinus. Cambridge University Press, Cambridge. 530 p. ISBN 0-521-55176-5
  • Mirov, N. T. 1967. The Genus Pinus. Ronald Press, New York (out of print).
  • Farjon, A. 1984. Pines. E. J. Brill, Leiden. ISBN 90-04-07068-0

External links

Links to other Pinaceae

Pinus - Picea - Cathaya - Larix - Pseudotsuga - Abies - Cedrus - Keteleeria - Pseudolarix - Nothotsuga - Tsugabg:Бор (растение) da:Fyr (Pinus) de:Kiefern es:Pino eo:Pino fr:Pin it:Pinus he:אורן nl:Pinus ja:マツ nn:Furu pl:Sosna pt:Pinheiro (rvore) ru:Сосна sl:Bor (drevo) fi:Mnty sv:Tallar tr:am

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