Pines belong to the genus Pinus, in the Pinaceae family. They are coniferous trees that make up the monotypic Pinoideae subfamily. Sadly, almost all of its 115 species are known to succumb to diseases that take a toll on the plant's health and longevity.
Most species of Pine are native to the Northern Hemisphere. They are a common sight across the Canary Islands, Scotland, Russia, the Philippines, Norway, Siberia, northernmost Africa, and Southeast Asia.
They are also an extensive part of North American vegetation that spans from 66°N in Canada, 12°N in Nicaragua, and across Mexico and California. They are known to live for thousands of years, even in the subtropical and temperate regions of the Southern Hemisphere that they have been recently introduced to.
Pine trees are targeted by a number of pests, that infest the species throughout a lifetime.
The southern pine beetle or Dendroctonus frontalis Zimmermann is recognized as one of their most destructive enemies. Each attack involves thousands of beetles invading individual trees. The beetle pairs construct galleries along the inner bark to deposit eggs in individual niches.
The blue-stain fungi on the bodies of the beetles hasten death by clogging the water-conducting tissues. Another problem arises out of European Pine Sawfly infestation. The larvae eat through the needle surfaces, causing them to wilt. The larvae continue to feed from tip to base, feeding on older foliage and consequently stripping the needles.
The end result is the 'bottle brush' effect, with all old needles missing. Needle Scale infestations result in the loss of considerable amounts of plant sap. This gives the infected trees a frosted or silvery appearance. The white scales completely cover needles, leading to discoloration and branch death.
Another enemy is the Spruce Spider Mite. This insect is known to feed on more than 40 different species of conifers, including all types of pine. The White Pine Weevil, another common disease bearer causes growth reduction and stem deformation.
All these diseases increase the plant's susceptibility to wood decay organisms and increases tree mortality considerably. However, most of these insect-pests thrive on the pine, since it plays a suitable host to brood development.
Pines are resinous evergreens. They can grow to a height of 80m. Variants such as the Siberian Dwarf Pine, Sugar Pine, and Potosi Pinyon are known to survive extreme temperatures for over a thousand years.
The Great Basin Bristlecone Pine (Pinus longaeva) is the oldest known example at 4,840 years in 2008! It is contending for 'Oldest Living Organism' in the modern world. Their barks can be thick and scaly, or thin and flaky, depending on the temperature variations they are subjected to. The branches are pseudo whorls, arising from the same node.
While some species are uninodal - producing one whorl of branches a year, others are multinodal - producing more than one branch whorl a year. The needle and cone scales are great detectors of soil fertility and vigor. Pines have four types of leaves: cotyledons, juveniles, scales, and needles.
Most species are monoecious, with male and female cones co-existing on the same tree. A female cone takes around three years to mature after pollination. These trees are easily among the most commercially important trees.
They are force-cultivated for their timber and wood pulp, across the globe. Their wood is used extensively to design furniture and frame panels. Its resin is an important source of turpentine. The trees add to the aesthetic appeal of parks and gardens. They are also commercially harvested as Christmas trees.