An evergreen plant is one whose leaves remain green for the entire year. This is the case even in instances where such a plant retains its leaves only in warm seasons as opposed to deciduous plants which shed all their leaves in dry weather or during winter. Evergreen plants are comprised of both shrubs and trees, chief among them being conifers. Conifers are plants which bear cones; they are woody plants and the majority of which are trees in addition to a small number of shrubs. They are evergreens with over 600 different species in existence all around the world. Conifers comprise some of the tallest and oldest tree species some growing up to 300 feet in height like the Coast redwood. The Bristlecone pine can live for a staggering 5,000 years.
Distribution of Coniferous Trees
With the numerous species, conifers are distributed in different places around the world, but they are mostly found in the Northern Hemisphere extending all the way to the Arctic Circle. They are also in both Central and Southern America, a few varieties in Africa as well as vast distributions in Asia and Europe. Some of the conifers which were introduced to New Zealand have become invasive and they include radiata pine, lodgepole pine, European larch, and Douglas dir. In South Africa species such as patula pine, maritime pine, and radiata pine have been named as invasive species.
Characteristics of Coniferous trees
Coniferous trees have several characteristics chief among these being their leaves which are why they are referred to as evergreens since they retain their foliage all year round by shedding and growing new ones simultaneously. Leaves of some coniferous plants are needle-shaped like the pine, spruce, and fir while others such as cypress have scale-like leaves, these do not form single leaves but entire branches of more than one year.
Conifers bear cones that are seeds and they are dispersed both by wind and animals. The seed cones have bracts, which bear semblance to actual seeds. They are partly hidden in some species like hemlock, or barely visible in firs while they are seen to be elongated and very prominent in the Douglas fir. When matured these seeds become large and woody.
Another trait in coniferous trees is the sticky secretion that is found on the bark of the tree. Resin ducts are the tubes that house the cells which secrete this pitch to the surface of the tree. It is used by the tree as a healing agent and close up wounds inflicted during the process of shedding cones, leaves, and even bark. On the surface, the resin is sometimes harvested for use in extraction of oils and other commercial use.
Uses of Conifers
Conifers are exploited for different reasons. Some of the uses include the production of paper and lumbering for purposes of construction. The conifers are robust and long-lasting and are therefore a favorite in making furniture. In addition to these, they have also been used in making anti-cancer medicine. Due to their several uses conifers have come under threat as a result of human activities of exploitation coupled with degradation of forest areas, which in effect have put about 34% of these species at the brink of extinction.