Taxodiaceae is a formerly recognized conifer family. It is today recognised as a paraphyletic grade of basal lineages within the Cupressaceae. It contains the following living genera:
As proposed, genera of the former Taxodiaceae are grouped in the following subfamilies within the larger Cupressaceae:
Sequoia sempervirens (/səˈkwɔɪ.ə ˌsɛmpərˈvaɪrənz/) is the sole living species of the genus Sequoia in the cypress family Cupressaceae (formerly treated in Taxodiaceae). Common names include coast redwood, coastal redwood and California redwood. It is an evergreen, long-lived, monoecious tree living 1,200–2,200 years or more. This species includes the tallest living trees on Earth, reaching up to 115.9 m (380.1 ft) in height (without the roots) and up to 8.9 m (29 ft) in diameter at breast height. These trees are also among the longest-living trees on Earth. Before commercial logging and clearing began by the 1850s, this massive tree occurred naturally in an estimated 810,000 ha (2,000,000 acres) along much of coastal California (excluding southern California where rainfall is not sufficient) and the southwestern corner of coastal Oregon within the United States. Being the tallest tree species, with a small range and an extremely long lifespan, many redwoods are preserved in various state and national parks; many of the largest specimens have their own official names.
The name sequoia sometimes refers to the subfamily Sequoioideae, which includes S. sempervirens along with Sequoiadendron (giant sequoia) and Metasequoia (dawn redwood). Here, the term redwood on its own refers to the species covered in this article but not to the other two species.
Glyptostrobus is a small genus of conifers in the family Cupressaceae (formerly in the family Taxodiaceae). 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 Bolikhamsai province of eastern Laos near the Vietnam border.
Metasequoia, or dawn redwood, is a genus of fast-growing coniferous trees. It contains one extant (living) species, Metasequoia glyptostroboides, which is one of three extant species of conifers known as redwoods in the world. Metasequoia glyptostroboides is native to Lichuan county in Hubei, China. Although the shortest of the redwoods, it grows to at least 165 feet (50 meters) in height. Local villagers refer to the original tree from which most others derive as Shuǐshān (水杉), or "water fir", which is part of a local shrine. Since its rediscovery in 1944, the dawn redwood has become a popular ornamental, with examples found in various parks in a variety of countries.
Together with Sequoia sempervirens (coast redwood) and Sequoiadendron giganteum (giant sequoia) of California, Metasequoia is classified in the Cupressaceae subfamily Sequoioideae. M. glyptostroboides is the only living species in its genus, but three fossil species are known. Sequoioideae and several other genera have been transferred from the former family Taxodiaceae to Cupressaceae based on DNA analysis.