Tree a Week: Pine

Bristlecone Pine

Characteristics and Interesting Facts

  • Pine trees are evergreen, coniferous resinous tree growing 3–80 m tall. The smallest are Siberian dwarf pine and Potosi pinyon, and the tallest is an 81.79 m tall ponderosa pine.
  • Pines are found in large variety of environments, ranging from semi-arid desert (Turkish pine, bristlecone pine) to rainforests (Sumatra pine), from sea level up to 5,200 metres (mountain pine), from the coldest (Siberian dwarf pine) to the hottest (Caribbean pine) environments on Earth. Check out this website for more information on each species.
  • Pines are long lived and typically reach ages of 100–1,000 years, some even more. The longest-lived is the Great Basin bristlecone pinePinus longaeva. One individual of this species, dubbed “Methuselah“, is one of the world’s oldest living organisms at around 4,600 years old.
  • Conifers developed about 300 million years ago, and pines perhaps around 153 million years ago. The genus Pinus is thought to have diverged from other pines approximately 95 million years ago.
  • The spiral growth of branches, needles, and cone scales may be arranged in Fibonacci ratios.

Uses

  • Pines are among the most commercially important tree species valued for their timber and wood pulp throughout the world. The large scale mono-culture plantations can often become ecological dead zones with very little wildlife.
  • 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 flour or thickener in stews, soups, and other foods, such as bark bread. Adirondack Indians got their name from the Mohawk Indian word atirú:taks, meaning “tree eaters”.
  • Shikimic acid, the main ingredient in Tamiflu, is harvested from pine needles in Asia.
  • A tea made by steeping young, green pine needles in boiling water (known as tallstrunt in Sweden) is high in vitamins A and C.
  • Pine resin is used by bowed string instruments to increase friction.

Identification

Bark: The bark of most pines is thick and scaly. The branches are produced in a very tight spiral called whorls. Many pines produce just one such whorl of branches each year, from buds at the tip of the year’s new shoots. The new spring shoots are covered in brown or whitish bud scales and point upward at first, then later turn green and spread outward.

Leaves: Pines have four types of leaf:

  1. Seed leaves (cotyledons) on seedlings are borne in a whorl of 4–24.
  2. Juvenile leaves, which follow immediately on seedlings and young plants, are 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.
  3. Scale leaves, similar to bud scales, are small, brown and not photosynthetic, and arranged spirally like the juvenile leaves.
  4. Needles, the adult leaves, are green (photosynthetic) and bundled in clusters called fascicles. The needles can number from one to seven per fascicle. 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.

Cones: 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.

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