The three redwood subfamily genera are: Sequoia and Sequoiadendron of California and Oregon, USA; and Metasequoia in China. The redwood species contains the largest and tallest trees in the world. These trees can live to an age of thousands of years. This is an endangered subfamily due to habitat losses from: fire ecology suppression, logging, and air pollution.
Record holders 
The genera Sequoia and Sequoiadendron are massive trees. The genus Metasequoia, with the living species Metasequoia glyptostroboides, are smaller trees. The trees in Sequoioideae hold the record for the tallest and largest trees in the world. The tallest tree in the world is a Sequoia sempervirens, the Hyperion Tree. The largest tree in the world is a Sequoiadendron giganteum, the General Sherman Tree.
- The native habitat of Sequoiadendron giganteum trees is only on the western slopes of the Sierra Nevada range in central eastern California.
- The native habitat of Sequoia sempervirens trees is only in the Northern California coastal forests ecoregion, on the Northern California coast and several miles into Oregon.
- Metasequoia glyptostroboides trees are so rare they were thought to be extinct, until rediscovered by a Chinese forester in 1948. They were found on mountainous slopes in remote parts of the Hubei region of China.
Sequoioideae is an ancient taxon. The first Seqoioideae, Sequoia jeholensis, was discovered in Jurassic deposits. The fossil record shows a massive expansion of range in the Cretaceous and dominance of the Arcto-Tertiary flora, especially in northern latitudes. Genera of Sequoioideae were found in the Arctic Circle, Europe, North America, and throughout Asia and Japan. A general cooling trend beginning in the late Eocene and Oligocene reduced the northern ranges of the Sequoioideae, as did subsequent ice ages. The entire paleohistory of Sequoioideae has been a story of migration rather than adaptation. Evolutionary adaptations to ancient environments persisted in all three species despite changing climate, distribution, and associated flora. Morphological stasis over millennia ultimately forced these species into extremely limited ranges where they persist, though in a very vulnerable state.
Introduced range 
The two California redwood species, since the early 19th century, and the Chinese redwood species since 1948, have been cultivated horticulturally far beyond their native habitats. They are found in botanical gardens, public parks, and private landscapes in many similar climates worldwide. Plantings outside their native ranges particularly are found in California, the coastal Northwestern and Eastern United States, areas of China, Germany, and the United Kingdom. They are also used in educational projects recreating the look of the megaflora of the Pleistocene landscape.
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- Chaney, Ralph W. 1950. A revision of fossil Sequoia and Taxodium in Western North America based on the recent discovery of Metasequoia. Transactions of the American Philosophical Society. 40(3): 171-263.
- Jagels, Richard and María A. Equiza. 2007. Why did Metasequoia disappear from North America but not from China? Bulltin of the Peabody Museum of Natural History. 48(2): 281-290.
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