常綠巨型喬木，在原產地可高達 100 公尺，直徑可達 10 公尺。樹冠闊圓錐形。樹幹基部有垛柱狀膨大物；樹皮深縱裂，厚 30 至 60 公分，呈海綿質；冬芽小而裸露：小枝初現綠色，後變為淡褐色。葉鱗狀錐形，螺旋狀排列，下部貼生小枝，上部分離，分離部分長 3 到 6 公釐，先端銳尖，兩面有氣孔線。雌雄異株。
目前天然原生的世界爺群落只分布於加州內華達山脈西部，一塊長約 420 公里，海拔約 1400 到 2150 公尺高的狹小範圍內。除少數群落分布於優勝美地國家公園及其以北之地區外，大多數的自然群落座落於國王峽谷國家公園、巨杉國家公園及其鄰近的國家森林範圍。它們生長的地方通常是有著乾燥夏天、下雪的冬天、潮濕的氣候，海拔約1,500公尺到2,000公尺的山谷中。
加州紅木（Sequoia）據信為紀念切羅基文字發明者塞闊雅（Seguoyah）而命名。
紅杉（紅木）這個名詞廣義上也被用作為紅杉亞科（Sequoioideae）的通稱。該亞科包括了生長在加州海岸山脈地區的紅杉屬（Sequoia）、加州內華達山脈西側的巨杉屬與中國地區的水杉屬三種近親物種。
主要分布於北加州的太平洋海岸。北界至Chetco River（約加州和俄勒岡州交界），南界到Salmon Creek Canyon（加州蒙特瑞縣南部），最內陸離海不到75公里。
這個區域的年雨量達到2,500公厘，寒冷的海風和霧氣使得這個區域保持終年潮濕。
Giant Sequoias and Redwoods: The Largest and Tallest Trees
Giant sequoias and California redwoods (also called coast redwoods) are nature’s skyscrapers. These enormous trees exist primarily in Northern California, and though they have a number of common characteristics, including distinctive cinnamon-red bark, they are different species.
One giant sequoia (Sequoiadendron giganteum), known as General Sherman, is the world's largest tree, while a redwood ( called Hyperion ）is the tallest.
Giant sequoias
Giant sequoias can grow to be about 30 feet (9 meters) in diameter and more than 250 feet (76 meters) tall. The biggest of these behemoths is General Sherman, a giant sequoia in Sequoia National Park. General Sherman stands 275 feet (84 meters) tall, has a 102-foot (31 meters) circumference, and weighs an incredible 2.7 million pounds (1.2 million kilograms). Giant sequoias can live to 3,000 years, with the oldest on record living more than 3,500 years.
Mature sequoias lack branches on the lower half of their trunks. Sequoia trunks taper as they rise, forming a rounded top where individual branches sweep downward. Their green leaves are small, scale-like, and arranged in spirals. Both male and females cones are carried on the same tree.
Sequoias grow naturally along the western slope of the Sierra Nevada mountains, between 5,000 and 7,000 feet above sea level and far inland. That elevation provides the trees with dry mountain air necessary for their cones to open and release seeds. The snowpack from the Sierra Nevada provides sequoias with the thousands of gallons of water they drink every day. Sequoias have shallow roots and require well-drained soil.
Because of its brittle texture, the sequoia is not a valuable lumber species. It was, nevertheless, logged extensively around the turn of the 20th century. Originally, sequoias could be found throughout the Northern Hemisphere. Today, they are found only in 77 scattered groves in Northern California. Among the places that preserve giant sequoias are Sequoia National Forest, Sequoia National Park, and Giant Sequoia National Monument.
Redwoods
These tallest of trees reach heights of more than 350 feet (107 meters). The tallest tree in the world is named Hyperion, which reaches 379.7 feet (115.7 meters). Redwoods can achieve a diameter of 24 feet (7 meters), and 1.6 million pounds (725,700 kg). These giants can live to be 2,000 years old and have graced the planet for more than 240 million years. Though they once thrived throughout much of the Northern Hemisphere, today redwoods are only found on the coast from central California through southern Oregon. They do not live more than 50 miles inland, and are usually found in long belts, rather than small groves.
True to their name, coast redwoods need a moderate, coastal climate to survive. They require the area’s frequent fog to protect them from dry spells and drought. Like sequoias, redwoods require abundant water to drink and have shallow root systems. Redwoods, however, get their water from rain rather than snowmelt, and therefore require consistent rainfall throughout the year. They even “create” their own rain by trapping fog in their lofty branches. With the right amount of moisture, redwoods can grow two or three feet in a year, making them one of the fastest-growing conifers in the world.
In contrast to their size, redwoods have extremely small cones — about one inch long. They have appropriately large root systems, however, often extending 100 miles (161 kilometers) and intertwining with the roots of other redwoods. Baby redwoods often sprout at their parents’ base, latching onto their roots for nutrients. For this reason, they often grow in circular clusters sometimes called fairy rings.
The coast redwood’s lumber has been highly valued historically. It is durable, resistant to rot and termites, non-warping, and relatively soft. For this reason, it has been extensively logged. Since logging began in the 1850s, 95 percent of old-growth coast redwoods have been cut down, according to the Sempervirens Fund. Today, many redwoods exist in protected forests and parks.
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