The coast redwood, the world's tallest tree, is one of the three sequoia tree species, together with the giant sequoia(Sequoiadendron giganteum) and the dawn redwood (Metasequoia glyptostroboides). The coast redwood (Sequoia sempervirens) grows in natural stands in a long, thin coastal area along the Pacific Ocean in the west and northwest of the US (mostly California). It is the tallest tree in the world.
With its relatively slender silhouette this tree can grow even 20 meters higher than the tallest giant sequoias, that are nevertheless the biggest trees in the world, when looking at the volume of the trunk. The tallest known living tree, named Hyperion, is 115.55 m or 379.1 feet (measured in 2006) tall! This gets close to 120 to 130 m, that, according to a 2004 biological study, is the maximum attainable height  of a tree.
Foggy coastal forests of the Pacific
During the whole year it rains quite a lot in this thin coastal strip and it is quite foggy most of the time. This way the tree can absorb enough water and does not suffer that much from evaporation stress. Most of the tallest trees can be found in the wet river valleys on fertile, alluvial deposits, although unexpectedly a couple of recently discovered record breaking trees appeared to grow on the valley slopes. The coast redwood forests have an abundant undergrowth (amongst which there are a lot of ferns). However, the biggest biodiversity can be found tens of meters up: differents species of plants, lichens, salamanders, ... live high up in the sky between the complex branch systems of the redwoods. Prof. Steve Sillett, who studies these redwood canopies, compares them with "hanging gardens".
The get an impression of the size of these redwoods: the images above show some of these trees. On the left is the "Del Norte Titan" in the Jedediah Smith Redwoods State Park, California (© Bob Van Pelt). Notice the people in the left bottom corner. The tree on the right is called "Screaming Titans", also in Jedediah Smith Redwoods State Park.
The Del Norte Titan has a height of 93.6 m and a girth at breast height of 22.7 m. He is definitely not the tallest coast redwood, or the thickest, but has the second largest trunk volume ("The Lost Monarch" comes in first, depending on your definition of a "single tree"). Nevertheless he is surpassed in volume by the giant sequoia (Sequoiadendron), of which about fifteen specimens have a bigger volume with"General Sherman" on top of the list.
On first sight, the needles of the coast redwood do not resemble those of the giant sequoia: they are bigger and flat, much like that of a yew. The crown is conical just like the one of the giant redwood, with an almost equally massive trunk with a reddish brown, soft bark. The egg shaped cones are smaller (2 to 3 cm). In contrast to most other conifers, the coast redwood starts to grow again after being cut. The maximum age is probably around 2500 years.