Conifers, represented by 200 species in North America and more than 600 worldwide, evolved in the Pennsylvanian Period, some 300 million years ago; indeed, they have colonized our planet twice as long as flowering plants, which appeared in the Jurassic. Many of our modern conifers have graced the planet for 100 million years or more and now include the tallest (California Redwood), largest (Giant Sequoia) and longest-lived (bristlecone pine) trees on Earth.
Characterized by needle-like or lace-patterned leaves, conifers produce male and female cones which, depending on the species, may occur on the same plant. The male cones release a copious amount of pollen which, carried by the wind, fertilizes the female cones; seeds are born on scales of the female cone and are dispersed by birds, red squirrels, chipmunks or by the cone itself when it falls to the ground; in some species, such as lodgepole pines, the heat of wildfire is a crucial step in releasing the seeds. Though most conifers are evergreen, shedding old needles and growing new ones in a patterned sequence, there are deciduous species, including some larches and cypress trees. While true fruits are not produced by conifers, the small females cones of junipers and yews look like globular fruit and are often referred to as berries; robins, solitaires and waxwings are especially fond of these cones.
The resin produced by most conifers, offering protection from insects and disease, increases the flexibility of their branches, making conifers more tolerant of heavy snow while still retaining their photosynthetic needles. This trait, combined with their simplified mode of reproduction, makes conifers more capable of surviving in areas with a short growing season and they thus dominate forests across northern latitudes and at high elevations of mountain ranges. Indeed, through heavily logged for lumber and paper, Earth's vast boreal forests provide a vital carbon sink, helping to keep global warming in check.
