Conifer
The earliest conifers appear in the fossil record during the Late Carboniferous over 300 million years ago. These primitive plants likely originated in dry upland habitats as small trees known as walchian conifers. Their range expanded into lowlands during the Early Permian due to increasing aridity across the landscape. Walchian conifers were gradually replaced by more advanced voltzialean or transition conifers over time. Conifers remained largely unaffected by the massive Permian, Triassic extinction event that wiped out many other species. They became dominant land plants throughout the Mesozoic era, ruling forests for millions of years. Modern groups of conifers emerged from the Voltziales during the Late Permian through Jurassic periods. A major decline occurred in the Late Cretaceous corresponding to the explosive adaptive radiation of flowering plants. This shift allowed angiosperms to take over many ecosystems previously held by conifers.
Several extant conifers have relict taxon status surviving in small areas where they once may have been common and widespread. Wollemia nobilis was discovered in 1994 within narrow steep-sided sandstone gorges in Australia. The wild population consisted of under 60 adult trees with essentially no genetic variability implying a genetic bottleneck some thousands of years ago. Metasequoia glyptostroboides is known from fossils of Late Cretaceous and Miocene age yet survives as an extant tree with a small relict range in China. The Dutch botanist Aljos Farjon states the popular phrase living fossils could fittingly be applied to many of these. Extant gnetophytes consist of three relict genera namely Ephedra Gnetum and Welwitschia. Fossils definitely of this group date back to the Late Jurassic with many species present in the Cretaceous. Many conifer species became extinct leaving 30 out of 80 genera with just one extant species. Eleven more genera contain just two or three species today.
The name conifer meaning cone-bearing derives from Latin words for cone and to bear. As recently as 1999 the botanist Aljos Farjon wrote that he doubted conifers formed natural groups comparable to Rosaceae. By 2016 the conifers were recognized as a clade with six families not including gnetophytes. There are now over 600 living species across 65 to 70 genera. Phylogenomic analysis indicates the gnetophyte group is part of the conifer clade sister to the pine family. This gnepine hypothesis suggests gnetophytes once shared distinctive characters of conifers before losing them. The family Taxodiaceae is here included within the family Cupressaceae. Depending on interpretation the Cephalotaxaceae may or may not be included within the Taxaceae. Some authors recognize Phyllocladaceae as distinct from Podocarpaceae. All extant conifers except gnetophytes are perennial woody plants with secondary growth.
Boreal conifers have multiple adaptations to survive winters including strong tracheid vessels to tolerate ice pressure. A waxy covering on needle leaves minimizes water loss during cold seasons. The tree's conical shape helps shed snow effectively in heavy winter conditions. Most conifers retain functional foliage throughout the year making them evergreens. Leaves vary from 2 mm in scale-leaved species up to 600 mm long in needles of some pines like longleaf pine. Stomata appear in lines or patches and can close when it is very dry or cold. Dark green leaves help absorb maximum energy from weak sunshine at high latitudes. Conifers from lower latitudes often have yellower-green leaves while others develop blue or silvery leaves reflecting ultraviolet light. Five genera including Larix and Metasequoia are deciduous shedding their leaves in autumn. The world's tallest living tree is a coast redwood reaching heights over 100 meters.
Conifers produce seeds inside a protective cone called a strobilus with male and female cones usually on the same tree. All conifers rely on wind pollination to move pollen grains to female structures. In families such as Taxaceae the cone scales are much modified as edible arils resembling berries. These are eaten by birds which then pass the seeds in their droppings. Some seedlings survive to grow into trees after the female cone opens releasing them. Reproductive development slows to a halt during each winter season and resumes each spring. The cycle takes one year in genera such as Abies Picea Cedrus and Tsuga. Most pine species require two years for female strobilus development from initiation to seed maturation. Three pine species including Pinus pinea take three years to complete this process. Fire-adapted pines like Pinus radiata store seeds in closed cones released only when fire opens them.
Conifers dominate the taiga forest of the Northern Hemisphere forming the world's largest terrestrial biome. Larch is the most common tree in Russia and easily the most abundant tree genus worldwide by volume. The larch species Larix gmelinii reaches 75 degrees north latitude on the Taymyr Peninsula. Around 200 conifer species live only in the tropics while others inhabit Australasia Africa and Central South America. Species richness decreases with latitude so Canada has just 9 species whereas Mexico has 43. New Caledonia holds 42 endemic species despite being a tropical island. Needle cast diseases often caused by fungi in the Rhytismataceae family result in leaf fall. Bark beetles are destructive pests of commercial forestry affecting spruce and other conifers globally. At least 20 species of roundheaded wood-boring longhorn beetles feed on the wood of spruces firs and hemlocks. Some introduced conifers like Pinus radiata have become invasive species in New Zealand and Australia.
The softwood derived from conifers is more easily worked than hardwood from broadleaved trees making it widely used. Uses include construction furniture telegraph poles and fencing for human infrastructure needs. A large part of production goes toward paper manufacturing across global markets. In the United Kingdom 48% of woodland that is coniferous yields over 90% of timber produced. Sitka spruce is the top species yielding about half of the timber produced there. Worldwide wood products reached a value of $100 billion by the end of the 20th century. Conifers such as fir cedar cypress juniper spruce pine yew and false cedar selected by plant breeders for ornamental purposes. Plants with unusual growth habits sizes and colors are propagated and planted in parks worldwide. The world's oldest non-clonal living tree is a Great Basin bristlecone pine 4700 years old. These ancient specimens demonstrate the longevity potential within conifer lineages today.
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Common questions
When did the earliest conifers appear in the fossil record?
The earliest conifers appear in the fossil record during the Late Carboniferous over 300 million years ago. These primitive plants likely originated in dry upland habitats as small trees known as walchian conifers.
What is Wollemia nobilis and when was it discovered?
Wollemia nobilis was discovered in 1994 within narrow steep-sided sandstone gorges in Australia. The wild population consisted of under 60 adult trees with essentially no genetic variability implying a genetic bottleneck some thousands of years ago.
How many living species of conifers exist today according to recent classifications?
There are now over 600 living species across 65 to 70 genera. Phylogenomic analysis indicates the gnetophyte group is part of the conifer clade sister to the pine family.
Which tree holds the title for the world's tallest living conifer?
The world's tallest living tree is a coast redwood reaching heights over 100 meters. This species represents the maximum height potential found among all extant conifer lineages.
When does reproductive development resume for most conifer species after winter?
Reproductive development slows to a halt during each winter season and resumes each spring. The cycle takes one year in genera such as Abies Picea Cedrus and Tsuga.
What percentage of timber produced in the United Kingdom comes from coniferous woodland?
In the United Kingdom 48% of woodland that is coniferous yields over 90% of timber produced. Sitka spruce is the top species yielding about half of the timber produced there.