Sequoias are trees in the genus Sequoia, although most people use the term specifically to refer to the Giant Sequoia. Giant Sequoias are the largest trees in North America, and they are among the biggest organisms in the world. Trees in this genus contribute a great deal to the ecologies in which they live; a sequoia can provide shelter for animals and help to trap valuable nutrients, among many other things. Some people also find sequoias aesthetically pleasing, and several parks including Redwood National Park, the Humboldt Redwoods, and Muir Woods feature some excellent examples of sequoias.
Trees in the Sequoia genus are conifers, which means that they produce cones. Sequoias can also reproduce with burls, large protruding growths which fill with young buds. Burls are often harvested for their unique wood, which is filled with fascinating, contorted patterns. Sequoias also have deeply furrowed bark which has a distinct fibrous texture, and their wood has a rich red color, which led to the common name “redwood.” The trees have green, slightly scaly needles, and they can grow both formidably wide and tall, even if they aren't classified as Sequoia giganteum, or Giant Sequoias.
The origin of the scientific name “Sequoia” is actually rather interesting. The trees were named for Chief Sequoya, a famous Cherokee man who developed a Cherokee syllabary so that his native language could be written down. When these towering trees were discovered and botanists were seeking a name, they decided to honor the chief. Some botanists dispute this tale, but no firm evidence on either side of the argument has been presented. The Oxford English Dictionary supports the Chief Sequoya story, and since it is widely considered to be an authority on language, this claim may well be correct.
Sequoias are native to a small stretch of moist, cool real estate between Northern California and Southern Oregon. In addition to Giant Sequoias, this region also hosts the Coast Redwood, also called Sequoia sempervirens. Coast Redwoods can grow to be even taller than Giant Sequoias, although they tend to be less wide than their relatives. These trees tend to grow in dense forests which can feel almost primeval to visitors, especially on cloudy, foggy days.
Fog is actually an important part of the ecosystems which sequoias inhabit, since the trees trap water on their feathery branches and drop it on the forest floor. The trees are often surrounded with a rich carpet of fungi, ferns, and braken, along with small shrubs and incredibly rich, crumbly soil. Redwood forests also host an assortment of animals, ranging from owls to deer.