Fitzroya is a genus in the cypress family Cupressaceae with a single species, Fitzroya cupressoides native to the Andes mountains of southern Chile and adjoining Argentina, where it is an important member of the Valdivian temperate rain forests. The scientific name of the genus honours Robert FitzRoy; common names include Lahuan (the Mapuche Native American name), Alerce (South American Spanish), and Patagonian Cypress.
It is a very large evergreen tree, the largest tree species in South America, growing to 40-60 m tall and up to 5 m trunk diameter. The leaves are in decussate whorls of three, 3-6 mm long (to 8 mm long on seedlings) and 2 mm broad, marked with two white stomatal lines. The cones are globose, 6-8 mm diameter, opening flat to 12 mm across, with nine scales in three whorls of three. Only the central whorl of scales is fertile, bearing 2-3 seeds on each scale; the lower and upper whorls are small and sterile. The seeds are 2-3 mm long, flat, with a wing along each side. The seeds are mature 6-8 months after pollination.
In 1993 a specimen from Chile was dated as 3622 years old. This gives it the third-greatest fully verified age recorded for any living tree, after the Great Basin Bristlecone Pine and the as yet unnamed 9,550 year old spruce tree discovered in Sweden in 2008. Much larger specimens existed in the past before the species was heavily logged in the 19th and 20th centuries; Charles Darwin reported finding a specimen 12.6 m in diameter, which, if accurately measured, would have made it the stoutest tree ever measured anywhere in the world.
A team of researchers from the University of Tasmania found fossilized foliage of Fitzroya on the Lea River of northwest Tasmania. The 35 million year-old fossil has been given the species name Fitzroya tasmanensis. The finding demonstrates the ancient floristic affinities between Australasia and southern South America, which botanists identify as the Antarctic flora.