Sequoiadendron Giganteum (World's Most Massive Tree), Western -Slopes of The Sierra Nevada Mountains of California

Sequoiadendron Giganteum is the sole living species in the genus Sequoiadendron, and one of three species of coniferous trees known as redwoods, classified in the family Cupressaceae in the sub-family Sequoioideae, together with Sequoia sempervirens (coast redwood) and Metasequoia glyptostroboides (dawn redwood). The common use of the name "sequoia" generally refers to Sequoiadendron giganteum which occurs naturally only in groves on the western slopes of the Sierra Nevada Mountains of California.

The etymology of the genus name has been presumed initially in The Yosemite Book by Josiah Whitney in 1868—to be in honor of Sequoyah (1767–1843), who was the inventor of the Cherokee syllabary. An etymological study published in 2012, however, concluded that the name was more likely to have originated from the Latin sequi (meaning to follow) since the number of seeds per cone in the newly-classified genus fell in mathematical sequence with the other four genera in the suborder.

Giant sequoias are the world's largest trees by volume. They grow to an average height of 50–85 m (160–279 ft) and 6–8 m (20–26 ft) in diameter. Record trees have been measured to be 94.8 m (311 ft) in height and over 17 m (56 ft) in diameter. The oldest known giant sequoia based on ring count is 3,500 years old. Sequoia bark is fibrous, furrowed, and may be 90 cm (3.0 ft) thick at the base of the columnar trunk. It provides significant fire protection for the trees. The leaves are evergreen, awl-shaped, 3–6 mm long, and arranged spirally on the shoots. The seed cones are 4–7 cm long and mature in 18–20 months, though they typically remain green and closed for up to 20 years; each cone has 30-50 spirally arranged scales, with several seeds on each scale, giving an average of 230 seeds per cone. The seed is dark brown, 4–5 mm long and 1 mm broad, with a 1-mm wide, yellow-brown wing along each side. Some seeds are shed when the cone scales shrink during hot weather in late summer, but most are liberated when the cone dries from fire heat or is damaged by insects.

The giant sequoia regenerates by seed. Young trees start to bear cones at the age of 12 years. Trees up to about 20 years old may produce stump sprouts subsequent to injury, but unlike coast redwoods, shoots do not form on the stumps of mature trees. Giant sequoias of all ages may sprout from their boles when branches are lost to fire or breakage.

At any given time, a large tree may be expected to have about 11,000 cones. Cone production is greatest in the upper portion of the canopy. A mature giant sequoia has been estimated to disperse 300,000–400,000 seeds per year. The winged seeds may be carried up to 180 meters (590 ft) from the parent tree.

Lower branches die fairly readily from shading, but trees less than 100 years old retain most of their dead branches. Trunks of mature trees in groves are generally free of branches to a height of 20–50 meters (66–164 ft), but solitary trees will retain low branches.

Because of its size, the tree has been studied for its water pull. Water from the roots can be pushed up only a few meters by osmotic pressure but can reach extreme heights by using a system of branching capillarity (capillary action) in the tree's xylem (the water tubules) and sub-pressure from evaporating water at the leaves. Sequoias supplement water from the soil with fog, taken up through air roots, at heights to where the root water cannot be pulled.

The natural distribution of giant sequoias is restricted to a limited area of the western Sierra Nevada, California. They occur in scattered groves, with a total of 68 groves (see list of sequoia groves for a full inventory), comprising a total area of only 144.16 km2 (35,620 acres). Nowhere does it grow in pure stands, although in a few small areas, stands do approach a pure condition. The northern two-thirds of its range, from the American River in Placer County southward to the Kings River, has only eight disjuncture groves. The remaining southern groves are concentrated between the Kings River and the Deer Creek Grove in southern Tulare County. Groves range in size from 12.4 km2 (3,100 acres) with 20,000 mature trees, to small groves with only six living trees. Many are protected in Sequoia and Kings Canyon National Parks and Giant Sequoia National Monument.

The giant sequoia is usually found in a humid climate characterized by dry summers and snowy winters. Most giant sequoia groves are on granitic-based residual and alluvial soils. The elevation of the giant sequoia groves generally ranges from 1,400–2,000 m (4,600–6,600 ft) in the north, to 1,700–2,150 meters (5,580–7,050 ft) to the south. Giant sequoias generally occur on the south-facing sides of northern mountains, and on the northern faces of more southerly slopes.

High levels of reproduction are not necessary to maintain the present population levels. Few groves, however, have sufficient young trees to maintain the present density of mature giant sequoias for the future. The majority of giant sequoias are currently undergoing a gradual decline in density since European settlement.

While the present day distribution of this species is limited to a small area of California, it was once much more widely distributed in prehistoric times, and was a reasonably common species in North American and Eurasian coniferous forests until its range was greatly reduced by the last ice age. Older fossil specimens reliably identified as giant sequoia have been found in Cretaceous era sediments from a number of sites in North America and Europe, and even as far afield as New Zealand and Australia.

The giant sequoia was well known to Native American tribes living in its area. Native American names for the species include wawona, toos-pung-ish and hea-mi-withic, the latter two in the language of the Tule River Tribe.

The first reference to the giant sequoia by Europeans is in 1833, in the diary of the explorer J. K. Leonard; the reference does not mention any locality, but his route would have taken him through the Calaveras Grove. This discovery was not publicized. The next European to see the species was John M. Wooster, who carved his initials in the bark of the 'Hercules' tree in the Calaveras Grove in 1850; again, this received no publicity. Much more publicity was given to the "discovery" by Augustus T. Dowd of the Calaveras Grove in 1852, and this is commonly cited as the species' discovery. The tree found by Dowd, christened the 'Discovery Tree', was felled in 1853.

The first scientific naming of the species was by John Lindley in December 1853, who named it Wellingtonia gigantea, without realizing this was an invalid name under the botanical code as the name Wellingtonia had already been used earlier for another unrelated plant (Wellingtonia arnottiana in the family Sabiaceae). The name "Wellingtonia" has persisted in England as a common name. The following year, Joseph Decaisne transferred it to the same genus as the coast redwood, naming it Sequoia gigantea, but again this name was invalid, having been applied earlier (in 1847, by Endlicher) to the coast redwood. The name Washingtonia californica was also applied to it by Winslow in 1854, though this too is invalid, belonging to the palm genus Washingtonia.

In 1907, it was placed by Carl Ernst Otto Kuntze in the otherwise fossil genus Steinhauera, but doubt as to whether the giant sequoia is related to the fossil originally so named makes this name invalid. The nomenclature oversights were finally corrected in 1939 by J. Buchholz, who also pointed out the giant sequoia is distinct from the coast redwood at the genus level and coined the name Sequoiadendron giganteum for it.

The etymology of the genus name has been presumed initially in The Yosemite Book by Josiah Whitney in 1868 to be in honor of Sequoyah (1767–1843), who was the inventor of the Cherokee syllabary. An etymological study published in 2012, however, concluded that the name was more likely to have originated from the Latin sequi (meaning to follow) since the number of seeds per cone in the newly-classified genus fell in mathematical sequence with the other four genera in the suborder.

 

Wood from mature giant sequoias is highly resistant to decay, but due to being fibrous and brittle, it is generally unsuitable for construction. From the 1880s through the 1920s, logging took place in many groves in spite of marginal commercial returns. The Hume-Bennett Lumber Company was the last to harvest giant sequoia, going out of business in 1924. Due to their weight and brittleness, trees would often shatter when they hit the ground, wasting much of the wood. Loggers attempted to cushion the impact by digging trenches and filling them with branches. Still, as little as 50% of the timber is estimated to have made it from groves to the mill. The wood was used mainly for shingles and fence posts, or even for matchsticks.

Pictures of the once majestic trees broken and abandoned in formerly pristine groves, and the thought of the giants put to such modest use, spurred the public outcry that caused most of the groves to be preserved as protected land. The public can visit an example of 1880s clear-cutting at Big Stump Grove near General Grant Grove. As late as the 1980s, some immature trees were logged in Sequoia National Forest, publicity of which helped lead to the creation of Giant Sequoia National Monument.

The wood from immature trees is less brittle, with recent tests on young plantation-grown trees showing it similar to coast redwood wood in quality. This is resulting in some interest in cultivating giant sequoia as a very high-yielding timber crop tree, both in California and also in parts of western Europe, where it may grow more efficiently than coast redwoods. In the northwest United States, some entrepreneurs have also begun growing giant sequoias for Christmas trees. Besides these attempts at tree farming, the principal economic uses for giant sequoia today are tourism and horticulture.

General Sherman is a giant sequoia (Sequoiadendron giganteum) tree located in the Giant Forest of Sequoia National Park in Tulare County, in the U.S.state of California. By volume, it is the largest known living single stem tree on Earth. While the General Sherman is the largest currently living tree, it is not the largest historically-recorded tree. The Crannell Creek Giant, a coast redwood (Sequoia sempervirens) near Trinidad, California, is estimated to have been 15 to 25% larger than the General Sherman tree by volume. That tree was cut down in the mid-1940s. Another larger coast redwood, near 90,000 cubic feet, the Lindsey Creek tree, was reported in a 1905 Humboldt Times Standard article.

While it is the largest tree known, the General Sherman Tree is neither the tallest known living tree on Earth (that distinction belongs to the Hyperion tree, a Coast redwood), nor is it the widest (both the largest cypress and largest baobab have a greater diameter), nor is it the oldest known living tree on Earth (that distinction belongs to a Great Basin bristlecone pine). With a height of 83.8 meters (275 ft), a diameter of 7.7 m (25 ft), an estimated bole volume of 1,487 m3 (52,513 cu ft), and an estimated age of 2,300–2,700 years, it is nevertheless among the tallest, widest, and longest-lived of all trees on the planet.

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Sequoiadendron Giganteum
General Sherman
List of Largest Giant Sequoias