Pine and its Description

A pine tree is any coniferous tree or shrub in the genus Pinus (/piːnuːs/) of the family Pinaceae.Pinus is the only genus in the subfamily Pinoideae.World Flora Online, created by the Royal Botanic Gardens, Kew Gardens and Missouri Botanic Gardens, accepts the latest species names for 187 pines, plus many more synonyms.121 species accepted by the American Conifer Society (ACS) and the Royal Horticultural Society.Pine trees are common in the northern hemisphere.Pine can also refer to wood extracted from pine trees; it is one of the more widely used types of wood. Pinaceae is the largest family of conifers, with 818 named species (or trinomials) currently recognized by the ACS.

Description 

Pines are evergreen coniferous resinous trees (or less commonly shrubs) 3–80 m (10–260 ft) tall, with most species reaching 15–45 m (50–150 ft).The smallest are the Siberian dwarf pine and the Potosis pine, and the tallest is the 81.8 m (268 ft) tall Ponderosa pine in the Rogue River-Siskiyou National Forest in southern Oregon.Pine trees are very long-lived, often reaching 100-1,000 years, some even longer.The longest-lived is the Great Basin bristlecone pine (P. longaeva).An individual of this species, known as "Methuselah," is one of the oldest living creatures in the world, around 4,800 years old.This tree can be found in the White Mountains of California.An old tree, now felled, dates back to 4,900 years.It was found in the woods below Wheeler Peak and is now named "Prometheus" after the Greek immortal.The spiral growth of branches, needles, and cone scales may be arranged according to Fibonacci ratios.New spring shoots are sometimes called "candles"; they are covered with brown or white bud scales, pointing upward at first, then turning green and spreading outward.These "candles" give foresters a way to assess soil fertility and tree vigor.

Bark

Most pine trees have thick, scaly bark, but some have thin, thin bark.The branches arise in the form of a regular "false thread", which is actually a very tight spiral but looks like a circle of branches emanating from the same point. Many pines are single-noded, producing only one ring of such branches each year from the buds at the top of that year's new shoots, but others are knotty, producing two or more rings of branches each year.

Foliage

• Pine trees have four types of leaves:

• Seed leaves (cotyledons) on seedlings in whorls of 4-24.

• Young leaves follow seedlings and shoots, 2-6 cm (3⁄4-2+1⁄4 in.) long, single leaves, green or often blue-green, arranged in spirals on shoots.The lead time for these products is six months to five years, rarely longer.

• Scale leaves similar to bud scales, small, brown, non-photosynthetic, spirally arranged like young leaves.

• The needles, the adult leaves,are green (for photosynthesis) and come in bundles called bundles.The number of stitches per fascicle can range from one to seven, but is usually from two to five.Each bundle arises from a small bud on a dwarf bud in the axil of the scale leaf.These bud scales usually remain on the fascicles as basal sheaths.The needles last 1.5-40 years, depending on the species.If the growing tip of a shoot is damaged (e.g. eaten by an animal), the bundle of needles below the damage produces a stem bud which can then replace the lost growing tip.

Cones

Pine trees are monoecious, with male and female cones on the same tree. 205 Male cones are small, usually 1-5 cm long, and exist only for a short time (usually in spring, though in a few autumn pines), falling down once they shed pollen.Female cones take 1.5-3 years (depending on the species) to mature after pollination, with actual fertilization delayed by one year.When mature, the female cones are 3-60 cm long. Each cone has many 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 spread by wind (wind dispersal), but some are larger and have only vestigial wings, and are spread by birds.The female cones are woody and sometimes armed to protect the developing seeds from foragers.When ripe, the cones usually open to release the seeds.In some bird-dispersed species, such as whitebark pine,the seeds are released only when the cones are broken by the birds.In other cases, seeds are stored in closed cones for years until an environmental signal triggers the cones to open, releasing the seeds.This is called serotonin.The most common form of serotiny is pyrescence, in which a resin binds the cones together until it is melted by a forest fire, eg P. rigida.