In the hottest of summers or the coldest of winters, there is one tree that remains steadfast, seemingly never changing. The evergreen is one of the world's most versatile tree types. In one form or another, they are found in virtually every location on earth suitable for growing vegetation. Even in the northernmost climates, a circle of evergreens rounds the top portion of the globe in an area known as the taiga, or boreal forest.
Though many might think evergreens are so named because they never drop their leaves, this is not true. Evergreens do shed their foliage on a regular, but not seasonal, basis. Needles on evergreens tend to last anywhere from two to 17 years. The oldest needles are usually found closest to the trunk.
The distinctive feature of evergreens is generally that they do not lose their foliage in the winter. Most also have very narrow, wax-like foliage that can be soft or hard to the touch. Further, the shape of many evergreens tends to be very much like a cone, which is why many are called conifers.
Evergreens are able to make it through the winter without dropping their leaves because of their design efficiencies. They have smaller leaves, which means less chance for moisture loss. Also, the leaves are usually coated with a wax-like substance to further prevent moisture from escaping. Further, the ability to keep leaves means they spend less energy each year growing a new batch and their shapes help them drop snow easier.
There are many different types of evergreens, with the most common being conifers, such as pines and spruces. Various types of ivy plants also are considered evergreen. While they are broadleaved, they have a wax-like coating that helps them survive the winter. Tropical evergreens are deciduous plants that are generally broadleaved, but receive adequate moisture and sunlight so that leaf drop is not a problem.
Evergreens are very useful to humans. They serve as windbreaks in the winter, when deciduous trees offer minimal protection. Because of their ability of some species to grow quickly, evergreens also are often used in commercial tree-growing operations, as sources for wood used in furniture and paper. In fact, conifers account for two-thirds of all industrial wood harvested.
Generally, caring for evergreens is a simple process. Owners often shape evergreens as a matter of their own personal preference, not because it is actually needed. You should apply generous amounts of water during any replanting. Also, watch for evidence of evergreen disease, such as significant leaf browning.