Different species of pine trees can be found throughout the world and can grow in a wide variety of soil types and climates. Pine trees originated in Europe and Asia and were introduced to the Americas by immigrants. Although characteristics differ from species to species, their characteristics overlap.
Instead of the broad, flat leaves of most tree species, pines have acicular-shaped leaves, usually referred to as needles. The needles are generally bunched in groups of two to eight and joined at the base by a sheath. Different species will have different numbers of needles in each cluster. White pines, for example, usually have five needles per cluster, whereas ponderosa pines only have two.
Pine trees sprout new leaves in spirals around their branches. These spirals are called candles. Leaves will generally live for about two years, after which they turn brown and are discarded. Because pines are evergreen, they will constantly replace the dead candles with new ones. Pine leaves are also covered in a waxy layer called a cuticle. This wax prevents water loss and is the reason why they appear glossy.
Pine bark, too, has characteristics that set it apart from other barks. Many pine trees have a reddish-brown bark, as is the case with the long-leafed pine. Pine bark also has plates that either appear in layers or are scaly. The bark has a rough texture. Pine bark has a distinct smell, often described as turpentine. If you peel off a small section of the bark and smell the underside, you should get a strong scent. This is often the defining factor to tell whether it is pine bark or not.
Instead of producing fruit, pine trees produce cones. This is how pine trees reproduce. There are two types of cone, the male and the female, the latter of which is the form that is more commonly thought of when we refer to pine cones. The male cone is usually smaller and not as thick. Its job is to fertilize the female component through the release of pollen. The female cones are harder and longer lasting than the males. They capture the pollen and eventually drop the fertilized seeds. The female is covered in scales; at the bottom of each scale a seed is produced and it is released when the cone opens.
Pines are evergreen. This means that they maintain their leaves all year, not dropping them in the fall like most other tree types. Scientists theorize that they are evergreen because of the low-nutrient environments in which they grow; they stay green all year to continue to process nutrients.