Conifers are cone-bearing seed plants and a subgroup of gymnosperms, classified under the division Pinophyta. This division includes the class Pinopsida. Most conifers are perennial woody plants, primarily trees, but a few are shrubs. Examples include cedars, pines, spruces, and redwoods. As of 2002, there are around 600 living species within seven families and 60 to 65 genera.
Ecologically, conifers are crucial as they dominate large areas, especially in the taiga of the Northern Hemisphere. Their conical shape and downward-drooping limbs help them shed snow, and many species can adjust their biochemistry to resist freezing. Although they have less biodiversity compared to tropical rainforests, conifer forests serve as significant terrestrial carbon sinks. Economically, conifers are valuable for softwood lumber and paper production.
Conifers vary in size from under one meter to over 100 meters in height. The tallest, the coast redwood (Sequoia sempervirens), reaches up to 115.55 meters. The thickest tree is the Montezuma cypress (Taxodium mucronatum), with a diameter of 11.42 meters, while the giant sequoia (Sequoiadendron giganteum) has the largest volume at 1,486.9 cubic meters. The smallest is the pygmy pine (Lepidothamnus laxifolius), which rarely exceeds 30 centimeters. The oldest living non-clonal tree is a Great Basin bristlecone pine (Pinus longaeva) estimated to be 4,700 years old.
Most conifers are evergreen, typically featuring needle-like leaves, though some, like those from the Cupressaceae family, have flat, scale-like leaves.
