The conifers, which space woody plants consisting mostly of evergreen trees, make up the phylum Coniferophyta, one of four phyla that gymnosperms that have living representatives. Words “conifer”means cone-bearing. Many conifers bear your reproductive structures in cones.With 50 genera and 550 of the 700 recognized gymnosperm species, the phylum Coniferophyta has the mass of the gymnosperms. Coniferophyta is likewise the most widespread and, in regards to numbers of individual trees, the most abundant that the gymnospermphyla. The abundance and economic and ecological importance of the Coniferophyta space out of all proportion come the number of species, which does not start to compare to the 235,000 types of angiosperms (phylum Anthophyta).
Conifers prosper over practically the entire world. They are particularly abundant in north temperate and boreal regions. They predominate in the taiga, or north boreal forest, i beg your pardon covers enormous stretches of north North America and also northern Eurasia. They conquer that forest by virtue of huge numbers of people of only about a dozen species,mainly that spruce, fir, and also larch. They display greater diversity in mid latitude, mountain forests of the north Hemisphere. Conifers additionally occur in cool mountain areas of the tropics. In temperate regions of the southerly Hemisphere, they are widespread but less leading than in the north. Junipers and pines room the most wide-ranging conifers, occurring across the north continents and also into the tropics. In the southerly Hemisphere, the most widely distributed conifer genus is Podocarpus.Due to your abundance and broad range, their frequently arboreal habit, and also their stem structure, conifers space the only gymnosperms that yield wood on a commercial scale. They are the source of every one of the world’s softwood timber and also nearly half of the total yearly lumber supply.A lengthy Fossil RecordThe oldest known conifer fossils date to the late Carboniferous duration of the Paleozoic era, part 300 million years ago. The earliest well-known angiosperms are much less than fifty percent this old. Conifers diversity greatly throughout the Paleozoic’s reasonably dry, cold Permian duration (290-245 million years ago), which followed the Carboniferous. The drought-resistant, needlelike pipeline characteristic of many contemporary conifers may have actually evolved during that dried period.The contemporary families the conifers started to distinguish in the Mesozoic era (245 million come 65 million year ago). Conifers to be the leading vegetation throughout much of that era. They gradually gave means to the angiosperms, i m sorry achieved an international dominance by about ninety million years ago, throughout the Cretaceous duration of the Mesozoic, and also remain dominant today. In the early Tertiary duration of the Cenozoic era, i beg your pardon dawned around 66 million years ago, a varied coniferous flora covered large areas of the northern Hemisphere.Vegetative Features
Conifers have specific notable vegetative characteristics. Because that example, many, though not all, of them have actually needlelike leaves, and such leaves take place only in conifers. Part conifers have actually scalelike leaves, and a few have bladelike ones.The stems and roots that conifers are additionally note worthy, the same, similar thing the woody eudicots and also magnoliids the Anthophyta in developing a dense mass of an additional xylem—that is, wood.Reproductive CharacteristicsIn conifers, the ovules, i m sorry contain the eggs and also eventually ripen right into seeds, are not fastened in ovary tissues in ~ flowers together they are in the angiosperms. Instead, like various other gymnosperms, conifers have naked ovules. These ovules are borne on scales that room arranged spirally follow me the axes the cones. As result of a complicated evolutionary history, the framework of these cones is compound rather than simple.
In enhancement to ovulate, or female, cones, conifers create male cones, which are smaller, shorter-lived, and generally much less woody. The axis the a male cone bears lessened leaves, each v two pollen sacs on the undersurface. The pollen grains created within the sacs contain the immature sperm. In most conifers, cones of both genders are present on the same tree. Although gymnosperms various other than conifers may create cones, conifers space distinctive in combining straightforward pollen cones through compound ovulate cones. The yews (genus Taxus) bear their ovules singly, at the advice of branchlets, fairly than in cones. The seed that develop from this ovules room enclosed in a fleshy covering referred to as an aril.In the spring, the masculine cones that conifers relax their pollen to the wind. Few of it reaches mrs cones, which have their cone scales widely separated to obtain it. ~ pollination, the female cap close their scales. Fertilization generally occurs, within the ovule, around three days to three or 4 weeks ~ pollination. In the pines, however, the is delay for about fifteen months.In many conifers, the maturation seeds, through their included embryos, are dispersed in the loss of the year in i beg your pardon fertilization occurs. The most common dispersal certified dealer is the wind, aided in many types by wings on the seeds. Conifer seeds that lack wings typically depend top top dispersal agents such together birds or mammals. In some pines, the cones need the heat of a woodland fire to open up the scales and release the seeds.Pine FamilyOf the households of life conifers, the Pinaceae, or jaw family, is the largest, comprise ten come twelve genera, with around two hundred types world-wide. Many of these room resin-bearing trees.This family members is the most widespread and abundant conifer family in the northern Hemisphere and very important economically. It provides a great deal of lumber, pulpwood, and paper products. That is likewise important ecologically, providing essential cover, nesting habitat, and food because that many types of wildlife.
The jaw family’s range ismainly in Eurasia and also NorthAmerica. Genera that occur all across this expanse room Pinus (pines), Picea (spruces), Abies (firs), and also Larix (larches). Douglas firs (Pseudotsuga) and hemlocks (Tsuga) are restricted to phibìc America and Asia. The true cedars (Cedrus) take place only in warm-temperate areas of Eurasia and northern Africa. Three genera of the pine family members are minimal to China.Pinus, the earliest genus in the jaw family, developed at least 130 million year ago, in the early Cretaceous period. The grows primarily in the northern Hemisphere. The pines number more than ninety species, nearly fifty percent the total varieties of the Pinaceae. One of the world’s oldest recognized plants is the bristlecone pine (Pinus longaeva), which grow in Utah, Nevada, and a tiny area of western California. Some bristlecone pines are about forty-six hundred years old. In comparison to other conifers, pines create their adult needles in fascicles, or bundles. The variety of needles every fascicle depends on the species.Other Conifer FamiliesAccording to a frequently used group system, there room seven households of conifers in enhancement to the Pinaceae. A remarkable one is the Taxodiaceae, i beg your pardon is today stood for by widely scattered types that room the remnants of populations that to be much much more widespread during the Tertiary period. Outright cypress belongs come the Taxodiaceae, as execute two redwood species renowned for their size and also longevity. The coastline redwood (Sequoia sempervirens) grows along seaside California and Oregon, and also the “big tree” (Sequoiadendron giganteum) occurs on the western slope of the Sierra Nevada mountains in California.
The shore redwood is normally the taller of the two species, getting to up to 117 meters in height. The big tree, however, usually exceeds the shore redwood in complete mass and also can live to be numerous thousand years old.Another significant member that the Taxodiacae is the dawn redwood (Metasequoia glyptostroboides). This species was an initial known come science just from fossils found in the early on 1940’s. Not long afterward, the tree was found growing in China.A much more recent living-fossil discover belongs to the Araucariaceae, a conifer family limited to the SouthernHemisphere. This tree, the Wollemi jaw (Wollemia nobilis), had been believed to have actually gone die out fifty million years ago. Then, in 1994, a stand was found farming in Australia.
The Cupressaceae, or cypress family, has Chamaecyparis (false cypress), Juniperus (junipers, often dubbed “cedars” in north America), and Thuja (arbor-vitae). These plants are distributed throughout the world. Part are crucial as wood or ornamentals.The Taxaceae family, which has the yews, is widely spread in the northern Hemisphere. The Podocarpaceae is largely minimal to the southerly Hemisphere. The Sciadopityaceae and also Cephalotaxaceae space confined to eastern Asia.