There are three tree species that are commonly referred to as redwood. These are the coast redwood (Sequoia sempervirens), the giant Sequoia (Sequoiadendron gigantium) also called Big Tree or Sierra redwood, and the dawn redwood (Metasequoia glyptostroboides). All of these trees are members of the Taxodiaceae family, and each one is the sole species in its respective genus. The Taxodiaceae family includes a total of nine genera and contains approximately fifteen species. The exact number depends on which "authority" is consulted. The species in contention include: Cryptomeria fortunei (Cryptomeria japonica var. sinensis) and Taxodium ascendens (pond cypress). Genera, species and common names within the Taxodiaceae family are listed in the following table:

Coast Redwood - Coast redwood is native to a narrow strip of land that extends from southern Monterey County, California (lat. 35^o 41' north) to Chetco River in the southwest corner of Oregon (lat. 42^o 09' north). There are approximately 1,740,000 acres of coast redwood forests in California and Oregon of which 255,000 acres are in redwood parks. Although foresters do not recognize races of coast redwood, a number of different varieties have been described including: adpressa (tips of leaflets creamy white), glauca (bluish colored leaves), gracilis (slender branchlets), pendula (branches hanging downward) and taxifolia (very broad leaves).

Giant Sequoia - The giant Sequoia is native to a narrow strip that runs north and south in the mountains of western California. It occurs in about 70 scattered groves that occupy a total area of approximately 30,000 acres. Most of the groves are found at altitudes that range from 4,300 to 6,800 feet. The giant Sequoia was originally named Wellingtonia gigantea in 1852 by British botanist John Lindsey in honor of the Duke of Wellington. In 1854, the French botanist Joseph Decaisne decided that the tree was in the same genus as the coast redwood and named it Sequoia gigiantia. The U.S. Forrest Service ignored these and other botanist and used the name Washingtonia gigantea for many years. Finally, in 1939 Dr. J.T. Buchholtz discovered that the chromosome numbers of coast and Sierra redwood were different. He therefore renamed the new genus Sequoiadendron gigantium which was excepted by most of the scientific community with the exception of the British botanists who had been using Wellingtonia gigantea all along and insisted that if it was a separate genus as Lindsey had claimed almost 100 years before, then his original designation should be used.

Dawn Redwood - The dawn redwood has been found in fossilized form in Asia, Greenland and north America since the middle of the 19th century, but was initially assumed to be of the same genus as bald cypress. In 1941, Japenese paleobotanist Shigeru Miki came across a dawn redwood fossil near Kobe, Japan and observed that it was different from known types. He assigned it a new genus, Metasequoia, which means the newest Sequoia. In 1944, a forester named Tsang Wang found a large unfamiliar tree near the village of Mo-tao-chi in the province of Szechuan, in central China. This tree was later identified as the long-lost Metasequoia by H.H. Hu. Specimens of the newly discovered tree were sent to two American experts. One of these experts was palentologist Ralph W. Chaney of the University of California. Chaney had previously discovered Metasequoia fossils near the John Day river in Oregon. In 1948 Chaney and science editor Milton Silverman of the San Francisco Chronicle departed for China. They returned with cuttings, and possibly seed (one account says it was the wrong time of the year to collect seed). Some of the collected material was distributed worldwide to arboretums, nurseries and universities. Within a few years, this easily propogated tree could be found in numerous commercial nurseries. Currently there are numerous 100 ft. tall specimens growing in cities throughout the U.S..

Baldcypress - The only member of the Taxodiaceae family that is native to the southeastern United States is the baldcypress or swamp cypress, Taxodium distichum. In the past pond cypress, Taxodium ascendens, was also considered to be separate species. However, today it is considered to be a variety of Taxodium distichum. Not all experts agree, some still insist that pond cypress is a separate species because it does not cross-pollinate with swamp cypress.

China Fir - China Fir, Cunninghamia lanceolata, is another member of the Taxodiaceae family that is commonly grown in the U.S. as an ornamental. This tree exibits some of the characteristics of coast redwood such as prolific root sprouts at the base of the tree and sprouts from injured areas, such as where the base of the tree is scrapped with a lawnmower. In China this tree is widely cultivated for timber.

Tasmanian Cedars- These trees are all native to the mountains of Tasmania. The Tasmanian pencil pine or smooth Tasmanian cedar, Athrotaxis cupressoidesis, is native to the mountains of central and western Tasmania. The King William pine, Athrotaxis selaginodes, is the largest member of the family and grows to a height of 108 ft. It is native to western Tasmania. The summit cedar, Athrotaxis laxifolia, is intermediate in size between the other two members of the genus and is also native to the western mountains of Tasmania.

Cryptomeria - The Japanese cedar, Cryptomeria japonica, and Chinese cedar, Cryptomeria fortunei, are both large fast growing trees. Many authorities consider Cryptomeria fortunei to be a variety of Cryptomeria japonica (fortunei = japonica var. sinensis). The Chinese cedar grows to a height of 240 ft. and is probably the tallest tree native to China. Both of these trees have a foliage that is similar to the giant Sequoia. The Japanese cedar is easy to cultivate and like its American cousins thrives in moist, well drained, soils. Many different cultivar varieties (>26) of Cryptomeria japonica have been developed.

The genus Sciadopitys was previously considered to also be a member of the Taxodiaceae family but it is now considered to be in the Cupressaceae family. All genera within the Taxodiaceae family are evergreen with the exceptions of Glyptostrobus, Metasequoia, and Taxodium.

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