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Pine
Pinus densiflora Kumgangsan.jpg
Japanese Red Pine (Pinus densiflora), North Korea
Scientific classification
Kingdom: Plantae
Division: Pinophyta
Class: Pinopsida
Order: Pinales
Family: Pinaceae
Genus: Pinus
L.
Subgenera

See Pinus classification for complete taxonomy to species level. See list of pines by region for list of species by geographical distribution.

Pines are 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.

EtymologyEdit

The modern English name pine derives from Latin pinus by way of French pin; similar names are used in other Romance languages. 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 Norwegian fura/fure/furu, Swedish, furu, and Föhre in German, but in modern English, fir is now restricted to Fir (Abies) and Douglas-fir (Pseudotsuga).

Taxonomy, nomenclature & codification Edit

Main article: Pinus classification

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

DistributionEdit

Pines are native to most of the Northern Hemisphere. In Eurasia, they range from the Canary Islands, Iberian Peninsula and Scotland east to the Russian Far East, and in the Philippines, north to just over 70°N in Norway, Finland and Sweden (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 and Red 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, Tanzania, Australia, Argentina and New Zealand, where they are grown widely as a source of timber. A number of these introduced species have become invasive,[1] threatening native ecosystems.

MorphologyEdit

Pines are evergreen, resinous trees (or rarely shrubs) growing 3–80 m tall, with the majority of species reaching 15–45 m tall. The smallest are Siberian Dwarf Pine and Potosi Pinyon, and the tallest is a 268.35-foot (81.79-meter) tall Ponderosa Pine located in southern Oregon's Rogue River-Siskiyou National Forest.[2]

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 are long-lived, typically reaching ages of 100–1,000 years, some even more. The longest-lived is the Great Basin Bristlecone Pine, Pinus longaeva, one individual of which, at around 4,800 years old, is one of the world's oldest living organisms.

FoliageEdit

Pines have four types of leaf:

  • Seed leaves (cotyledons) on seedlings, borne in a whorl of 4–24.
  • 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.
  • Scale leaves, similar to bud scales, small, brown and non-photosynthetic, and arranged spirally like the juvenile leaves.
  • Needles, the adult leaves, which are green (photosynthetic), bundled in clusters (fascicles) of 1–6, commonly 2–5, 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.

ConesEdit

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.

EcologyEdit

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 (e.g. Siberian Dwarf Pine, Mountain Pine, Whitebark Pine and the bristlecone pines). The pinyon pines and a number of others, notably Turkish Pine and Gray 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), the Symphytan species Pine sawfly, and goats.

ReferencesEdit

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