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. The two other genera, Sequoiadendron and Metasequoia, in the subfamily Sequoioideae are closely related to Sequoia. S. sempervirens can live to an age of thousands of years but it is an endangered subfamily due to habitat losses from fire ecology suppression, logging, and air pollution.
Only two of the genera, Sequoia and Sequoiadendron, are known for massive trees. Metasequoia, with the living species Metasequoia glyptostroboides, are much smaller and are found in the home landscape.
The tallest tree in the world is a Sequoia sempervirens, the Hyperion Tree. (The largest tree in the world, by volume, is a Sequoiadendron giganteum, the General Sherman Tree.)
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.
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.
Sequoias were named after Sequoyah, a Cherokee scholar, who, basing on Latin and Cyrillic letters, created the alphabet for the people he originated from. As a result, the rates of literacy among Cherokees rose significantly, helping preserve their language and culture. John Davis, writing about Sequoyah, credited Austrian biologist Stephan Endlicher with naming the new species of redwood Sequoyah gigantea in 1847, to honor Sequoyah's invention of the Cherokee syllabary.
