Taxodiaceae
Encyclopedia
The Taxodiaceae were at one time regarded as a distinct plant family
comprising the following ten genera of coniferous tree
s:
However, recent research has shown that the Taxodiaceae, with the single exception of Sciadopitys, should be merged into the family Cupressaceae
. There are no consistent characters by which they can be separated, and genetic evidence demonstrates close relationships; this merging is now becoming widely accepted.
The one exception, the genus Sciadopitys, is genetically very distinct from all other conifers, and now treated in a family of its own, Sciadopityaceae
.
As proposed, genera of the former Taxodiaceae are grouped in the following subfamilies within the larger Cupressaceae:
In earth's history Taxodiaceae were widespread. They are known since the Jurassic
and can be found as fossil
e.g. in layers from Tertiary
times.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
comprising the following ten genera of coniferous tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s:
- AthrotaxisAthrotaxisAthrotaxis is a genus of two to three species of conifers in the cypress family, Cupressaceae. The genus is endemic to western Tasmania, where they grow in high altitude temperate rainforests....
- CryptomeriaCryptomeriaCryptomeria is a monotypic genus of conifer in the cypress family Cupressaceae formerly belonging to the family Taxodiaceae; it includes only one species, Cryptomeria japonica . It is endemic to Japan, where it is known as Sugi...
- CunninghamiaCunninghamiaThe genus Cunninghamia is a genus of one or two species of evergreen coniferous trees in the cypress family Cupressaceae. They are native to China, Taiwan and northern Vietnam, where they may reach 50–55 m in height....
- †CunninghamitesCunninghamitesCunninghamites is an extinct conifers genus in the family Taxodiaceae of the European Late Cretaceous flora.-External links:...
- GlyptostrobusGlyptostrobusGlyptostrobus, is a small genus of conifers in the family Cupressaceae. The sole living species, Glyptostrobus pensilis, is native to subtropical southeastern China, from Fujian west to southeast Yunnan, and also very locally in northern Vietnam and Borikhamxai Province of eastern Lao PDR near the...
- MetasequoiaMetasequoiaMetasequoia is a fast-growing, deciduous tree, and the sole living species, Metasequoia glyptostroboides, is one of three species of conifers known as redwoods. It is native to the Sichuan-Hubei region of China. Although the least tall of the redwoods, it grows to at least 200 feet in height...
- SciadopitysSciadopitysThe Koyamaki , or Japanese Umbrella-pine, is a unique conifer endemic to Japan. It is the sole member of the family Sciadopityaceae and genus Sciadopitys, a living fossil with no close relatives, and known in the fossil record for about 230 million years.Its genus name comes from the Greek prefix...
- SequoiaSequoia (genus)Sequoia is a genus of redwood coniferous trees in the Sequoioideae subfamily, of the Cupressaceae family. The only extant species of the genus is the Sequoia sempervirens in the Northern California coastal forests ecoregion of Northern California and Southern Oregon in the United States...
- SequoiadendronSequoiadendronSequoiadendron giganteum is the sole living species in the genus Sequoiadendron, and one of three species of coniferous trees known as redwoods, classified in the family Cupressaceae in the subfamily Sequoioideae, together with Sequoia sempervirens and...
- TaiwaniaTaiwaniaTaiwania is a large coniferous tree in the cypress family Cupressaceae, formerly listed in the segregate family Taxodiaceae. It is native to eastern Asia, growing in the mountains of central Taiwan, and locally in southwest China and adjoining Myanmar and northern Vietnam. It is endangered by...
- TaxodiumTaxodiumTaxodium is a genus of one to three species of extremely flood-tolerant conifers in the cypress family, Cupressaceae...
However, recent research has shown that the Taxodiaceae, with the single exception of Sciadopitys, should be merged into the family Cupressaceae
Cupressaceae
The Cupressaceae or cypress family is a conifer family with worldwide distribution. The family includes 27 to 30 genera , which include the junipers and redwoods, with about 130-140 species in total. They are monoecious, subdioecious or dioecious trees and shrubs from 1-116 m tall...
. There are no consistent characters by which they can be separated, and genetic evidence demonstrates close relationships; this merging is now becoming widely accepted.
The one exception, the genus Sciadopitys, is genetically very distinct from all other conifers, and now treated in a family of its own, Sciadopityaceae
Sciadopitys
The Koyamaki , or Japanese Umbrella-pine, is a unique conifer endemic to Japan. It is the sole member of the family Sciadopityaceae and genus Sciadopitys, a living fossil with no close relatives, and known in the fossil record for about 230 million years.Its genus name comes from the Greek prefix...
.
As proposed, genera of the former Taxodiaceae are grouped in the following subfamilies within the larger Cupressaceae:
- Athrotaxidoideae Quinn (Athrotaxis)
- Cunninghamioideae (Sieb. & Zucc.) Quinn (Cunninghamia)
- Sequoioideae (Luerss.) Quinn (Sequoia, Sequoiadendron, and Metasequoia)
- Taiwanioideae (Hayata) Quinn (Taiwania)
- Taxodioideae Endl. ex K. Koch (Taxodium, Glyptostrobus, and Cryptomeria)http://www.conifers.org/cu/index.htm
Evolution
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
and can be found as fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
e.g. in layers from Tertiary
Tertiary
The Tertiary is a deprecated term for a geologic period 65 million to 2.6 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...
times.