Conifers make up a family of plants that includes a wide range of shrubs and trees. These plants are classified an gymnosperms, meaning "naked seed" in Latin. The seeds of conifers are unlike angiosperms, which bear seeds covered by a protective coat, such as an apple or a walnut. As a group, conifers are represented by species on all continents except for Antarctica.
The fossil record indicates that many forms of conifers were represented throughout history. Conifers first appeared in history in the Devonian period more than 300 million years ago. By the Carboniferous period, conifers were well-established. Fossils of many species that were growing in the Mesozoic period between 250 and 65 million years ago are very similar to species still growing today.
Most conifers are evergreens, keeping their foliage all year, despite climatic changes. Some conifers produce leaves that resemble scales that are connected in random branching pattern. Others grow needles, long, thin, simple leaves that grow in clusters at the ends of branches. Their form and size can also vary greatly, from tiny shrubs to the magnificent redwoods, the tallest tree on the planet.
The seeds form within a cone, a series of tough, interleaved scales connected to a central core. Conifers usually produce separate male flowers, which produce pollen, and female flowers, which produce an ovary and bear the seed within the cone. Cones come in a wide variety of shapes and sizes. When the seeds are ripe and ready to be dispersed, the cones open and drop their contents. Some species, such as junipers and yews, do produce fleshy, berry-like forms of seeds.
Large areas of North America, Europe and northern Asia consist of coniferous forests. The more temperate and even tropical regions have conifers growing in them. The Southern Hemisphere also has conifers, though they tend to reside in the far southern areas of the continents, such as the tip of South America and on islands such as New Caledonia, which has 43 species of conifers alone.
An important source of wood, conifers provide the vast majority of lumber made today. Wood from conifers also provides pulp for paper, and cellulose for a variety of uses. Conifers are also appreciated for their intrinsic aesthetic value and are frequently used in landscaping. Some conifers bear edible seeds, commonly called pine nuts. They also have religious and spiritual significance, as in the use of the pine tree to celebrate Christmas.