Sequoiadendron giganteum

• 1. Introduction

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  Sequoiadendron giganteum, the giant sequoia, includes the General Sherman tree, which has a trunk volume of 1489 cubic metres and weighs an estimated 2100 tonnes. That tree is about 2,500 years old and stands in California. Giant sequoias are the most massive individual trees in the world. How does a tree reach that scale? Why does it grow naturally only on the western slopes of a single mountain range? Why did botanists get its scientific name wrong again and again? And why does a species with armored bark depend on fire to have any young at all?

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• 2. Anatomy of a Giant

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  A typical giant sequoia rises 50-85 metres, with a trunk 6-8 metres across. The tallest measured specimen reached 94.8 metres. The widest trunk at breast height belongs to the General Grant Tree, at 8.8 metres. Claims of 17-metre trunks trace back to research figures taken out of context. Another claim, from 2014-2016, held that some coast redwoods had thicker trunks than any known giant sequoia, but no academic literature has confirmed it. The two relatives differ in shape. Coast redwood trunks taper at lower heights, while giant sequoia trunks stay columnar and hold their width higher up.

  At the base of that column, the bark can be 90 centimetres thick, fibrous and deeply furrowed. The sap contains tannic acid, which gives significant protection from fire damage. The leaves are evergreen and awl-shaped, only 3-6 millimetres long, and they spiral around the shoots.

  Dendrochronology, the dating of trees by their growth rings, puts the oldest known giant sequoia at 3,200-3,266 years. Only individuals of Great Basin bristlecone pine and alerce are known to live longer. The wood resists decay so well that a nearly complete log found 800 metres south of Nelder Grove returned a radiocarbon date of 10,000 years. Together with fast growth and great size, that longevity gives the species a high potential for storing carbon.

  A 2009 ranking of the ten largest by trunk volume starts with General Sherman, then General Grant, The President and Lincoln. Stagg, Boole, Genesis, Franklin, King Arthur and Monroe follow in that order. Giant Forest alone holds five of the ten. The largest giant sequoia ever recorded was the Father of the Forest in Calaveras Grove, which fell many centuries ago. It reportedly stood over 435 feet tall and measured 110 feet around. In Alder Creek Grove, the Waterfall Tree holds the girth record at 155 feet, thanks to an enormous buttress at its base on steep ground. The Muir Snag in Converse Basin Grove is listed at more than 3500 years old.

  In 2020, researchers published the giant sequoia genome. It runs to 8.125 billion base pairs, assembled into eleven chromosome-scale scaffolds, the largest of any organism at the time of publication. The DNA came from a single fertilized seed gathered from a 1,360-year-old tree in Sequoia and Kings Canyon National Park, labelled SEGI 21. Teams at the University of California, Davis, Johns Hopkins University, the University of Connecticut and Northern Arizona University worked on it for three years. Grants from Save the Redwoods League and the National Institute of Food and Agriculture supported the work as part of a conservation effort. It was the first genome sequenced in the family Cupressaceae, and it held over 900 complete or partial predicted NLR genes, which plants use to stop microbial infections from spreading. The seed that supplied that DNA came from a species with a surprising trigger for releasing its seeds.

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• 3. Born of Fire

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  A mature giant sequoia may carry as many as 11,000 cones, and cone production is greatest in the upper canopy. Each cone is 4-7 centimetres long and takes 18-20 months to mature, yet it typically stays green and closed for as long as 20 years. A cone has 30-50 spirally arranged scales and averages 230 seeds. The seeds are dark brown, 4-5 millimetres long, with a yellow-brown wing along each side. Trees begin bearing cones at 12 years old. A mature tree disperses an estimated 300,000-400,000 seeds a year, and the winged seeds can travel as far as 180 metres.

  Some seeds shed in late summer, when hot weather shrinks the cone scales. Most are freed by insect damage or by the heat of fire. The longhorn beetle Phymatodes nitidus lays eggs on the cones, and its larvae bore into them. That cuts the water supply to the scales, so the cone dries and opens, and beetle-damaged cones keep opening slowly over several months. Some research suggests that many cones high in the crown must be partly dried by beetles before fire can fully open them. The Douglas squirrel helps too. It gnaws the fleshy green scales of younger cones all year, and some seeds drop as it eats.

  Fire does the largest share of the work. It sends hot air high into the canopy by convection, which dries and opens the cones. The release of seed then lines up with the best seedbed conditions. Loose ash on the ground may also shield fallen seeds from ultraviolet damage.

  Seedlings are fussy. They grow successfully only in full sun and mineral-rich soil free of competing vegetation. A seed may germinate in moist needle humus in spring, but the seedling dies as that layer dries out in summer. Squirrels, chipmunks, finches and sparrows eat freshly sprouted seedlings. Without fire, shade-loving species crowd out the young sequoias and the seeds fail to germinate. Young trees under about 20 years old can sprout from stumps after injury, and trees of any age can sprout from the trunk when branches are lost to fire or breakage.

  During the early and mid-20th century, fire suppression and livestock grazing ended the low-intensity fires in many groves. Ground fuel built up, and fire-sensitive white fir grew densely. Those firs can act as ladders that carry flames up to the crowns of mature sequoias. Natural fires may also keep carpenter ants in check. In 1970, the National Park Service began controlled burns in its groves, and current policies also allow natural fires to burn. One untamed burn severely damaged the Washington tree, then the second-largest tree in the world, in September 2003-45 days after the fire started. The January 2005 snowstorm then collapsed over half of its trunk. Far larger blazes were still to come.

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• 4. Scattered Groves

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  Giant sequoias grow naturally in 81 groves, which together cover only 144.16 square kilometres of the western Sierra Nevada. Botanists call this a paleoendemic species, a relic confined to a small area. In the northern two-thirds of the range, from the American River in Placer County south to the Kings River, there are only eight disjunct groves. The rest cluster between the Kings River and the Deer Creek Grove in southern Tulare County. Sizes vary widely. The largest grove covers 12.4 square kilometres and holds 20,000 mature trees, while the smallest have only six living trees. No grove is a pure stand, though a few small areas come close.

  The groves sit at 1400-2000 metres in the north and 1700-2150 metres in the south. The climate is humid, with dry summers and snowy winters, and most groves rest on granitic soils. The trees favor the south-facing sides of northern mountains and the north-facing sides of more southerly slopes. Many groves lie inside Sequoia and Kings Canyon National Parks and Giant Sequoia National Monument. More than 30 species of bird have been seen living in them. Sequoia groves do not need heavy reproduction to hold their numbers, but few have enough young trees to sustain today's density. Most have been thinning gradually since European settlement.

  Fossils tell of a far wider past. Specimens reliably identified as giant sequoia turn up in Cretaceous sediments across North America and Europe, and even in New Zealand and Australia. The species was reasonably common in North American and Eurasian conifer forests until the last ice age greatly reduced its range.

  In 1974, the United States Forest Service planted giant sequoias in the San Jacinto Mountains of Southern California, right after a wildfire left the land barren. In 2008, botanist Rudolf Schmidt and his daughter Mena Schmidt rediscovered them while hiking the Black Mountain Trail through Hall Canyon. Black Mountain Grove holds over 150 giant sequoias, some taller than 6.1 metres. Nearby Lake Fulmor Grove has seven, the largest 20 metres tall. Both lie about 175 miles southeast of Deer Creek Grove, the southernmost natural grove. The Forest Service had planted sequoias across Southern California, yet only these two groves are known to reproduce without human help. The San Jacinto Mountains mimic conditions in the Sierra Nevada. Black Mountain Grove shares its name with a separate natural grove in the southern Sierra, so the two must not be confused.

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• 5. Discovery and Names

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  In 1852, the grizzly hunter Augustus T. Dowd came upon the Discovery Tree in Calaveras Grove. It became the first widely publicized discovery of the species by non-natives. The tree was cut down in 1853 and exhibited across the United States. A feature in Hutchings' Illustrated California Magazine in 1859 spread the story further and promoted tourism to the grove.

  Dowd was not the first outsider to meet the trees. In 1833, Zenas Leonard, a member of the Joseph R. Walker Party, recorded a giant sequoia in his diary without naming a location. His route likely crossed Calaveras Grove, but nobody noticed the entry. In 1850, John M. Wooster carved his initials into the bark of the Hercules tree at Calaveras Grove. A year later, Robert Eccleston passed through Nelder Grove with a small detachment of the Mariposa Battalion during the Mariposa War. Neither encounter drew any publicity.

  Around 1870, the naturalist John Muir wrote of the species with open awe. He declared, "Do behold the King in his glory, King Sequoia! Behold! Behold! seems all I can say." He added that he had left all for Sequoia and was at his feet, fasting and praying for light.

  The botanical names were a tangle. In December 1853, John Lindley named the tree Wellingtonia gigantea. He did not realize the name was invalid, because Wellingtonia had already been used for an unrelated plant, Wellingtonia arnottiana, in the family Sabiaceae. The name Wellingtonia has nonetheless persisted in England as a common name. In 1854, Joseph Decaisne moved the tree into the coast redwood's genus as Sequoia gigantea, but Endlicher had used that name for the coast redwood in 1847. That same year, Winslow called it Washingtonia californica, a name already taken by a palm genus. In 1907, Carl Ernst Otto Kuntze placed it in the otherwise fossil genus Steinhauera, which was also invalid because it was doubtful the two were related.

  John Theodore Buchholz corrected these oversights in 1939. He pointed out that the giant sequoia differs from the coast redwood at the genus level and coined Sequoiadendron giganteum.

  The meaning of the genus name Sequoia has its own twist. Josiah Whitney, in The Yosemite Book in 1868, presumed it honored Sequoyah (1767-1843), the inventor of the Cherokee syllabary. A 2012 study debunked that "American myth." It concluded that the Austrian Stephen L. Endlicher took the name from the Latin sequi, meaning to follow, because the seeds per cone in the newly classified genus fell in mathematical sequence with the four other genera.

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• 6. Timber and Symbol

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  From the 1880s through the 1920s, loggers worked many groves despite marginal commercial returns. The Hume-Bennett Lumber Company was the last to harvest giant sequoia, and it went out of business in 1924. The wood resists decay but is fibrous and brittle, and trees often shattered when they hit the ground. Loggers dug trenches and filled them with branches to cushion the fall. Even so, as little as 50% of the timber is estimated to have reached the mill. What survived became shingles, fence posts and even matchsticks.

  Photographs of broken, abandoned giants in once pristine groves, and the thought of such modest uses, triggered a public outcry. It led to the preservation of most groves as protected land. Visitors can still see 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, and the publicity helped lead to the creation of Giant Sequoia National Monument.

  Young wood tells a different story. Recent tests on young plantation-grown trees show wood less brittle and similar in quality to coast redwood. That has sparked interest in growing giant sequoia as a high-yielding timber crop, in California and in parts of western Europe. Some entrepreneurs in the northwest United States grow them as Christmas trees. Today, though, the main economic uses are tourism and horticulture.

  In the 19th century, sequoias such as Forest King were cut down and shipped to cities and world expositions as exhibition trees. The displays celebrated the grandeur of the frontier while exposing a willingness to exploit nature. That paradox fueled debates that eventually led to Sequoia and Yosemite National Parks.

  Tunnel trees added another chapter. Carving a roadway through a trunk, as with the Wawona Tree, showed off the ability to master the wilderness, and these trees drew crowds in the automobile age. As the weakened trunks began to collapse, they came to stand for the unintended costs of ambition. The California Tunnel Tree in Mariposa Grove is the last survivor.

  Americans also gave one tree a sacred role. In 1926, Calvin Coolidge named the General Grant Tree the "Nation's Christmas Tree." Dwight Eisenhower later declared it a national shrine honoring the country's war dead. It remains the only living object with that designation.

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• 7. Wildfire Losses

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  The McNally Fire in 2002 opened a run of destructive wildfires in sequoia groves. The Rough Fire followed in 2015 and the Railroad Fire in 2017. Each burned in groves where decades of fuel buildup had raised the odds of devastating crown fires. Logging was once the main threat to the species. Now the greatest danger comes from the loss of regular fire and its consequences.

  The Castle Fire in 2020 is estimated to have wiped out 10-14% of the giant sequoia population, or about 7,500 to 10,600 mature trees. Among them was the King Arthur Tree, one of the tallest known sequoias. In 2021, the KNP Complex and the Windy Fire killed an estimated 3-5% more. Since the species' last assessment as endangered in 2011, another 13-19% of the population, or 9,761-13,637 mature trees, has been destroyed in those fires. The losses are attributed to fire suppression and drought. The International Union for Conservation of Nature lists the species as endangered, with fewer than 80,000 remaining in California. As of 2021, there were approximately 60,000.

  Prescribed burns offer a counterweight. During the 2022 Washburn Fire, officials credited prescribed burns in Yosemite National Park with limiting the fire's intensity and sparing Mariposa Grove from major harm. Experts warn that protecting healthy groves will require raising the use of prescribed burns by about 30 times current levels. Far from California, seed shipped in 1853 started a different story.

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• 8. Around the World

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  In 1853, the horticulturist Patrick Matthew of Perthshire introduced the giant sequoia to Britain from seeds sent by his botanist son John in California. A much larger shipment, collected from Calaveras Grove by William Lobb for the Veitch Nursery near Exeter, arrived in England in December 1853. Seed from that batch was distributed widely across Europe. Today the tree grows successfully across most of western and southern Europe, the Pacific Northwest, southwest British Columbia, the southern United States, southeast Australia, New Zealand and central-southern Chile. It does less well in eastern North America. A tree can endure minus 31 °C for short periods if heavy snow or mulch insulates the roots, and growers have selected varieties including blue, powder blue, weeping and the cold-tolerant 'Hazel Smith.'

  Growth in Britain is very fast. The tallest tree, at Benmore in southwest Scotland, reached 56.4 metres in 2014 at age 150 years. The largest British trees have volumes of only 90-100 cubic metres, and one example in the New Forest measures 90. An avenue of 218 giant sequoias was planted in 1865 near Camberley, Surrey, and modern housing now surrounds it. In 2024 there were 4,949 notable sequoias in the United Kingdom, with an estimated 500,000 younger ones. Reproduction there requires human help.

  Near Ribeauvillé, France, a tree planted in 1856 was measured in 2014 at 57.7-58.1 metres tall at age 158 years. That is the tallest giant sequoia ever measured outside the United States. In Germany, a tree near Bensheim was planted in 1852 as a gift of the British Royal Family to the Landgraviate of Hesse-Darmstadt. It is probably the oldest sequoia in Germany and possibly in continental Europe. King William I of Württemberg grew 5000-8000 seedlings in the greenhouses of the Wilhelma in Stuttgart for forestry trials. Italy planted many sequoias from 1860 through 1905. One young Italian tree reached 22 metres and 88 centimetres in diameter in just 17 years. Another survived the 1963 flood wave caused by the landslide at Vajont Dam.

  Farther north and east, winter cold limits growth. A tree in Poland has purportedly survived temperatures down to -37 °C under heavy snow. Twenty-nine sequoias about 30 metres tall grow in Lazarevac, a municipality of Belgrade in Serbia. In Slatina, Croatia, a tree seeded around 1890 was proclaimed a nature monument in 1967. Above the Bulgarian city of Kyustendil stand around 100 trees, the oldest about 100 years old.

  In Seattle, a sequoia of 100 feet marks the entrance to the downtown retail core. A tree at the Tyler Arboretum in Pennsylvania, at 29.1 metres, may be the tallest in the northeastern United States. In New Zealand, a tree at Rangiora High School was planted for Queen Victoria's Golden Jubilee. In Hobart, Tasmania, two trees planted at St David's Park in 1937 commemorate the coronation of King George VI and Queen Elizabeth. In December 2025, the City of Hobart reported that one of the two was showing significant signs of distress and was being monitored by arborists.

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