The redwoods are a subfamily of conifers, the Sequoioideae. They are in the Cypress family Cupressaceae. It is most common in the coastal forests of Northern California and is possibly the largest tree in the world. There are three living genera in the subfamily. There were once more species of redwood trees, but most have become extinct.
These trees are pyrophytes: they have adapted to survive forest fires. Because fire is common in the regions where they grow, redwood trees have developed thick, fire-resistant bark. Their cones open only after a fire. Because fire control is better these days, the trees are endangered because they do not reproduce so well.
