The Arco Giant, one of the largest known redwoods [Robert Van Pelt] (Van Pelt 2001).

Mature sun foliage from the canopy of an old-growth tree [C.J. Earle].

Mature shade foliage from an ornamental tree [C.J. Earle].

Mature seed cones on sun foliage, from Humboldt Redwoods State Park [C.J. Earle].

The very top of Hyperion in 2008 [Steve Sillett, 2008.09.16]

Sequoia, like all of the Cupressaceae, is cladoptosic: dead foliage falls with the accompanying shoot, rather than as individual leaves [Dr. Linda B. Brubaker].

Range of Sequoia sempervirens (Burns & Honkala 1990).

The Del Norte Titan, largest known redwood [Michael Taylor] (Taylor 1998).

A white redwood in Humboldt Redwoods State Park [C.J. Earle].

U.S. postage stamp, released 2006.

Here I am with a stump of Sequoia affinis at Florissant Fossil Beds National Monument in Colorado. A ranger at the Monument told me that hundreds more such stumps, still buried, have been identified by acoustic imaging [C.J. Earle, 2006.07.05].

Sequoia sempervirens

(D. Don) Endlicher 1847

Common Names

Coast redwood, redwood, California redwood (Little 1980), coastal sequoia, palo colorado.

Taxonomic notes

Syn: Taxodium sempervirens D. Don in Lambert 1824 (Watson 1993); Sequoia sempervirens (Lambert) Endlicher (Peattie 1950). It is the sole species in Sequoia Endlicher 1847. Described varieties, all horticultural, include adpressa, glauca, nana pendula, pendula and prostrata (Silba 1986).

Description

Tree to 60-100(110) m tall and 300-460(900) cm dbh. Trunk much enlarged and buttressed at the base and often with rounded swellings or burls, slightly tapering. Crown crown conic and monopodial when young, narrowed conic in age, irregular and open. Bark red-brown, to ca. 35 cm thick, tough and fibrous, deeply furrowed into broad, scaly ridges; inner bark cinnamon-brown. Branches downward sweeping to slightly ascending. Twigs slender, dark green, forking in a plane, ending in a scaly bud. Leaves 1-30 mm, generally with stomates on both surfaces, the free portion to 30 mm, those on leaders, ascending branchlets, and fertile shoots divergent to strongly appressed, short-lanceolate to deltate, those on horizontally spreading to drooping branchlets mostly linear to linear-lanceolate, divergent and in 2 ranks, with 2 prominent, white abaxial stomatal bands. Pollen cones nearly globose to ovoid, 2-5 mm, borne singly on short terminal or axillary stalks. Female cones 12-35 mm long, elliptical, reddish-brown, with many flat, short-pointed scales; pendant at end of leafy twig; maturing in one season; with 2-5 seeds per scale, light brown, 2-winged. Seeds flattened, 3-6 mm, leathery. 2n= 66 (Little 1980, Watson 1993).

The genus Sequoia has been described as follows: "Trees giant, evergreen. Branchlets terete, with obvious annual growth constrictions. Leaves alternate, mostly in 2 ranks. Adult leaves linear or linear-lanceolate to deltate, generally flattened, divergent to strongly appressed; abaxial glands absent. Pollen cones with 6-12 sporophylls, each sporophyll with 2-6 pollen sacs. Seed cones maturing and opening in 1 season, oblong to globose; scales persistent, 15-30, valvate, ± peltate, thick and woody. Seeds 2-7 per scale, lenticular, narrowly 2-winged; cotyledons 2(-4). x = 11" (Watson 1993).

Range

USA: SW Oregon and NW California, confined to coastal areas (within 60 km of the sea) experiencing a great deal of fog; at elevations generally below 300 m, occasionally to 1000 m. Mostly found in alluvial soils, where it forms pure stands or occurs with Pseudotsuga menziesii, Chamaecyparis lawsoniana, or other local conifers (Little 1980, Watson 1993). See also Thompson et al. (1999).

Big Tree

The largest volume single-stem tree was discovered June 1998 in Jedediah Smith Redwoods State Park, California, by Steve Sillett and Michael Taylor. This tree has an estimated stem volume of 1044.7 cubic meters and is 93.57 m tall with a dbh of 7.22 m (Van Pelt 2001). A larger volume is found in the Lost Monarch, 1205 m³ and 98 m tall (Sillett [no date]). This volume estimate, however, includes two large stems that arise near the trees's base, and there is a disagreement between the surveyors who measured this tree regarding whether those stems are reiterations from limbs near the base of the tree, or root sprouts from right next to the tree. In either event, they represent a single genetic individual (a clone) and their wood is completely fused.

Aside: "DBH" (diameter at breast height, 1.4 m) is a rather meaningless statistic with coast redwoods. The trees commonly have such structurally complex bases that diameter cannot be meaninfully measured less than several meters above ground level. Thus, estimates of total wood volume are more useful for comparing tree sizes.

The coast redwood is probably the tallest tree on earth, although one occasionally hears of extraordinarily tall eucalypts in Western Australia, and during historical times there have been Douglas-firs (Pseudotsuga menziesii) recorded as being taller than any coast redwoods now living. However, it is quite likely that the tallest coast redwoods were early victims of the axe, so it is difficult to say if the redwood was the tallest of conifers during early historical time. The following table (source, Michael Taylor 1998 updated by Steve Sillett (emails 2004.11, 2008.09) and Bob Van Pelt (pers. comm., 2006.10), provides summary information on all coast redwoods known to be over 110 meters tall, as measured by direct tape drop or Criterion 400 laser surveyor.

Name	Location	Height (m)	Diameter (m)
Hyperion	Redwood National Park	115.56	4.70 cm
Helios	Redwood National Park	114.58	4.50
Icarus	Redwood National Park	113.11	3.6
Stratosphere Giant	Humboldt Redwoods State Park	113.07	5.19
National Geographic Society Tree	Redwood National Park	112.76	4.30
Paradox Tree	Humboldt Redwoods State Park	112.58	3.78
Federation Giant	Humboldt Redwoods State Park	112.34	4.38
Mendocino Tree	Montgomery Woods State Preserve	112.01	3.17
Harry Cole Tree	Redwood National Park	111.65	4.94
Swamp Tree	Montgomery Woods State Preserve	110.77	3.02
Pipe Dream Tree	Humboldt Redwoods State Park	110.64	4.27
Redwood Creek Giant	Redwood National Park	110.4	5.21
Lost Hope Tree	Humboldt Redwoods State Park	110.4	5.03
Rockefeller Tree	Humboldt Redwoods State Park	110.34	4.14
Daedalus	Redwood National Park	110.34	--

Oldest

Several data point to a maximum age of somewhat more than 2000 years. A ring-counted age of 2200 years was reported for a specimen from N California collected by Fritz (Brown 1996). This was probably a stump count. I have a section cut from a log in Humboldt Redwoods State Park that has at least 2026 rings. HERE is a report on it, the only one available. This specimen has poor circuit uniformity with many missing rings, so it may be as old or older than Fritz' specimen. There is also said to be a cross-section on display at the visitor center in Henry Cowell State Park, Santa Cruz, CA, that has 1935 rings with the center of the log missing; the original tree was felled in Humboldt County (Kenyon Moon email 2007.11.04).

There has been some new work on the age question recently (2008.07). S. sempervirens has been found to crossdate quite well, provided that the increment core samples are taken well above the tree's base - the best results are found for cores taken at the base of the live crown, usually about 50 m off the ground. Increment core samples are limited by the available equipment, rarely delivering a core more than 60 cm long. However, because most of these large trees are 2-3 m in diameter at the base of the live crown, a 60 cm core often records more than 1,000 years of record. It is possible to extrapolate to a conservative minimum total age estimate based on knowing the tree's growth potential (the amount of stem wood deposited in a good year) and back-calculating to when the tree first attained its canopy-mature height, usually at 200-300 years old. Numbers to date suggest ages up to 2000 years which, given the conservative estimates in the extrapolation, suggest there should be a number of trees out there that are at least 2000 years old. Results to date also suggest that among large trees (bigger than maybe 3-4 m DBH) there is a fairly weak correlation between size and age, so the largest trees may not be especially old in comparison to other trees in their cohort.

With all really old trees, there arises the question, can they live forever? In principle, yes. There is little evidence supporting the existence of senescence in conifers, and all really old trees (discussion) live many times longer than the oldest living cells in the tree. In practice, though, there are certain environmental factors that can kill trees. When a tree is resistant to those factors, and/or when the factors are expressed weakly or rarely, then the tree may attain a great age. The environmental factors never go away, though, and it is a statistical inevitability that every tree will eventually meet its end. Big redwoods are killed mostly by some combination of fungus, wind, gravity, fire, and flood. The most common death is due to stem or root rots that leave the tree vulnerable to breakage by wind, gravity, fire, and flood. Gravity kills trees when they develop a lean, which never gets better and usually gets worse, eventually breaking or uprooting the tree, often during a big storm when winds stress the crown and flooded soils reduce friction between roots and soil. Fire usually kills by repetition: one fire opens a fire scar through the thick bark, and later fires enlarge the scar and allow fungi to enter the heartwood, so that the tree will eventually break off. Floods usually kill redwoods when streambank erosion undercuts and topples a tree on a floodplain. There are also freak accidents, like when a falling tree hits another tree and delivers an injury that eventually proves mortal. And of course there are chainsaws. None of these things are common (except chainsaws), but 2000 years is a long time.

A few years ago, dendrochronology suffered a bit of a scandal - or at least, what might pass for a scandal in this peaceful field of study - when a person having no knowledge of the subject represented themselves as an expert to someone at the Guinness Book of World Records, claiming to have found a 12,000 year old redwood tree, which they modestly named the Eternal God Tree. Guinness duly published the claim. Later that year, I was shown the tree and had the opportunity to sample it with an increment borer. The sample produced 515 years and the tree is rotten inside of that. Given the tree's relatively small size (about 3 meters in diameter, which, yes, is "small" in comparison with other trees nearby), I would very much doubt it could be a day over 2,000 years old, and my best guess is about 1,200 years - a tenth of its claimed age. Incidentally, the 2,026-year-old tree described above was assigned an age of 7,000 years by the same person. I only mention this because you may see these fanciful ages of 7,000 and 12,000 years reported in the news media.

Dendrochronology

Fritz (1940) found that the species is not generally useful due to poor circuit uniformity (i.e. the rings do not go all the way around). However, a more exhaustive study by Schulman (1940) found that circuit uniformity improves when samples are taken well above the base of the tree; he successfully crossdated samples from cross-sections taken (from logged trees) 100 feet (30 meters) above the ground, and found evidence of narrow rings in drought years. More recent work (ongoing, still unpublished) by Steve Sillett at Humboldt State University and colleagues has confirmed Schulman's findings and is investigating the use of stable isotope data to reconstruct long-term variation in climate-growth response within the redwood canopy.

Ethnobotany

There was a time when redwoods were the largest trees on earth, and nearly all (well over 90% of the largest trees) were cut in a frenzy of logging activity that lasted over a century, beginning when California was Spanish and not ending until the 1990s, when the last old-growth grove on timber production lands was cut. The most severe period of logging began in about 1850, driven by the demand for mine and building timber created by the California gold rush, and continued well into the 20th Century. Opposition to the logging began almost immediately (in 1852, Assemblyman Henry A. Crabb of San Joaquin County asked the California legislature to secure into public ownership all of the state's redwood forest lands) in the late 19th Century and started to bear fruit in 1900, when the Sempervirens Club was established (Sempervirens Fund [no date]). This was the first activist organization to formally work to preserve the trees, and two years later, the first redwood park (now Big Basin Redwoods State Park) was set aside. Muir Woods National Monument was preserved in 1907, and in 1918 the Save The Redwoods League was established. In subsequent decades the League and many other activist groups have fought to protect remaining old redwoods by advocating for state and federal parks, securing donations of land, and sometimes buying land outright. Today, the redwoods are one of the most symbolically important of all tree species, revered by millions of people for the aesthetic and other intangible values provided by these remaining groves of immense, majestic trees.

Observations

The species is well protected in its native range and can easily be seen in California's Redwood National Park, Muir Woods National Monument, and a long chain of State Parks of which some of the more noteworthy are, from north to south, Jedediah Smith Redwoods, Prairie Creek Redwoods, Humboldt Redwoods, Montgomery Woods, and Big Basin Redwoods. If you have never seen a grove of ancient redwoods, you should do so. It is one of the finest sights anywhere on the planet.

Remarks

The genus is widely thought to be named for Sequoyah, also known as George Guess, inventor and publisher of the Cherokee alphabet. Endlicher was also a philologist, so he likely knew of Sequoyah's achievements. Unfortunately, Endlicher's writings give no clue to the etymology of Sequoia, and some very eminent botanists have proposed plausible alternatives. Asa Gray, for instance, thought it came from the Latin sequi, 'following', since it is the sole living representative of a sizable group of extinct plants (Hartesveldt et al. 1975).

The genus has a rich fossil record in western North America, represented by the Eocene and Oligocene fossil taxon Sequoia affinis and the pollen morphogenera Taxidiaceaepollenites and Sequoiapollenites. Well-preserved examples of S. affinis cones, foliage and wood - including in situ stumps over 200 cm dbh - have been found at Florissant Fossil Beds National Monument (Anonymous [no date]), at Copper Basin in Nevada (Inyo [no date]), and at various other locations in the West. The resemblance to S. sempervirens is striking.

Redwood is one of the few vegetatively reproducing conifers, readily regenerating from stump sprouts in the wake of a major disturbance (typically fire). One peculiar consequence of this is the occurrence of 'white redwoods' (see photo), which are trees that originate as root sprouts and are competely nonphotosynthetic, deriving all of their carbohydrate from the roots of their photosynthetic associates (which are not necessarily related, as root grafting is common between redwoods). White redwoods are found only in old-growth forests, where the overstory biomass of photosynthetic redwoods is colossal (redwood forests have the highest aboveground biomass loadings in the world) and the white trees are generally less than 3 meters tall. However, white redwoods up to 20 meters tall are known to exist. The tree in the photograph is about 10 m tall. At the time of the photograph, the new year's foliage had not emerged; trees clad in fresh foliage are snow-white.

Redwood is the only naturally occurring hexaploid conifer. Redwoods (Sequoia sempervirens and Sequoiadendron giganteum) are the state tree of California (Watson 1993).

The sequoias (including Sequoia and Sequoiadendron) were another group, like Metasequoia, first known from the fossil record, although fossil material was not formally named until Steinhauera Presl 1838, ten years after Lambert described this species as Taxodium sempervirens (Hartesveldt et al. 1975).

The species was early (ca. 1826) introduced to Spain thanks to the collections of Tadeas Haenke during the Malaspina expedition; an account of these trees appears HERE.

Citations

Anonymous. [no date]. Welcome to Florissant Fossil Beds National Monument! [link too long to display], accessed 2006.10.03. Includes photos of Sequoia affinis fossils.

Fritz, E. 1940. Problems in dating rings of California coast redwood. Tree-Ring Bulletin 6(3):19-21. Available online at www.treeringsociety.org/TRBTRR/TRBvol6_3.pdf, accessed 2006.06.05.

Inyo. [no date]. Field Trip To The Copper Basin Fossil Flora, Nevada. members.aol.com/Waucoba7/cb/copperbasin.html (accessed 2006.10.03).

Schulman, E. 1940. Climatic chronology in some coast redwoods. Tree-Ring Bulletin 6(3):22-23. Available online at www.treeringsociety.org/TRBTRR/TRBvol6_3.pdf, accessed 2006.06.05.

Sempervirens Fund. [no date]. History of Sempervirens Fund. http://www.sempervirens.org/history.htm, accessed 2008.08.08.

Sillett, S. [no date]. Redwood photo tour. http://www.humboldt.edu/~sillett/photos/sese/championtrees/full/3_metric.jpg, accessed 2008.08.07.