(Pinales) The largest and most widely distributed order of gymnosperms, containing about 49 genera with about 570 species most of which are evergreen trees. These are divided among the six families Pinaceae, Taxodiaceae, Cupressaceae, Podocarpaceae, Cephalotaxaceae, and Araucariaceae. The Cupressaceae and Taxodiaceae are sometimes included as subfamilies in the Pinaceae.
Conifers are particularly abundant in the high latitudes of the northern hemisphere, where they form the climax vegetation. Typically conifers show a pyramidal growth pattern and bear simple leaves, often needles or scales. Most conifers are monoecious but bear the male and female reproductive organs in separate compact cones on different parts of we tree. Conifers are more advanced than the cycads and ginkgo in that they Produce pollen grains; thus antherozoids are replaced by the two sperm nuclei, which are delivered to the egg by the Pollen tube. It is thought this feature may have contributed to the success of
he conifers as compared with other gymnosperms.
Conifers are commercially important as a source of timber for the papermaking, building, and furniture industries. They are generally faster growing and develop a less dense wood than angiosperm trees and are thus commonly called softwoods. In cross section distinct pores are normally absent in the wood (consequently termed nonporous wood) in contrast to the *
ring-porous or *
diffuse-porous wood of angiosperms. See also
Taxales.
