Conifer
Conifers are gymnosperms. They are cone-bearing seed plants.
| Conifera | |
|---|---|
| |
| Trees of a Pinophyta species: Araucaria heterophylla (Araucariaceae) | |
| Scientific classification | |
| Kingdom: | |
| Division: | Pinophyta
|
| Class: | Pinopsida
|
| Orders & Families | |
|
Cordaitales † | |
All living conifers are woody plants which are perennial. Most are trees; some are shrubs. They are the Division Pinophyta or Coniferophyta.[1][2]
Living conifers are all in the order Pinales. Typical examples include cedars, cypresses, firs, junipers, kauris, larches, pines, redwoods, spruces, and yews.
Species of conifers can be found in almost all parts of the world, and are often the most common plants in their habitats, as in the taiga. Conifers are of great economic value, and their wood is mainly used for timber and paper-making The wood of conifers is known as softwood, though yew wood is actually quite hard. The division Coniferae contains about 700 living species.
Evolution
The earliest conifers were in the late Carboniferous (Pennsylvanian) period (about 300 million years ago),[3] Pinophytes, Cycads, and Ginkgos all developed at this time.[3] These plants live without being so dependent on water. Other adaptations are pollen (so fertilisation can occur without water) and the seed, which allows the embryo to be transported and developed elsewhere.[3]
Conifers appear to be one of the taxa that benefited from the Permian–Triassic extinction event. They were the dominant land plants of the Mesozoic era. Conifers were eventually overtaken by their descendants, the flowering plants, which first appeared in the Cretaceous. Flowering plants became dominant in the Cainozoic era.
Conifers were a main food of herbivorous dinosaurs, and their resins and poisons no doubt gave them some protection against herbivores. All the reproductive features of modern conifers had evolved by the end of the Mesozoic era.[4]
List of genera
- Araucariaceae
- Cupressaceae
- Athrotaxis (pencil pine)
- Cryptomeria (Japanese redwood)
- Cunninghamia
- Glyptostrobus (Chinese swamp cypress)
- Metasequoia (dawn redwood)
- Sequoia (coast redwood)
- Sequoiadendron (giant redwood)
- Taiwania
- Taxodium
- Pinaceae
- Abies (fir)
- Cathaya
- Cedrus (cedar)
- Keeteleeria
- Larix (larch)
- Nothotsuga (bristlecone hemlock)
- Picea (spruce)
- Pinus (pine)
- Pseudolarix (golden larch)
- Pseudotsuga (Douglas fir)
- Tsuga (hemlock)
Conifer Media
A coniferous forest pictured in the coat of arms of the Kainuu region in Finland
Phylogeny of the Pinophyta based on cladistic analysis of molecular data.
The narrow conical shape of northern conifers, and their downward-drooping limbs, help them shed snow.
Tāne Mahuta, the biggest kauri (Agathis australis) tree alive, in the Waipoua Forest of the Northland Region of New Zealand.
Pinaceae: needle-like leaves and vegetative buds of Coast Douglas fir (Pseudotsuga menziesii var. menziesii)
Araucariaceae: awl-like leaves of Cook pine (Araucaria columnaris)
In Abies grandis (grand fir), and many other species with spirally arranged leaves, leaf bases are twisted to flatten their arrangement and maximize light capture.
Cupressaceae: scale leaves of Lawson's cypress (Chamaecyparis lawsoniana); scale in mm
A thin transverse section showing the internal structure of conifer wood
A Monterey pine forest in Sydney, Australia
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Related pages
References
- ↑ Eckenwalder, James E. 2009. Conifers of the world: the complete reference, p13. Timber Press. ISBN 0881929743, ISBN 9780881929744. [1]
- ↑ Farjon, Aljos 2008. Natural history of conifers. Timber Press. ISBN 0881928690, ISBN 9780881928693
- ↑ 3.0 3.1 3.2 Henry R.J. 2005. Plant diversity and evolution. London: CABI.
- ↑ Williams, Claire G. 2009. Conifer reproductive biology. Springer Science.