Common Names
Giant sequoia, bigtree, Sierra-redwood (Watson
1993).
Taxonomic notes
The sole species in Sequoiadendron
Buchholz 1939. Syn: Wellingtonia gigantea Lindley 1853; Sequoia
gigantea (Lindley) Decaisne 1854, not Endlicher 1847. The latter
homonym reflects the species' former inclusion in Sequoia, a
conservative placement that still has merit (Watson
1993).
Although the giant sequoia was probably
discovered in 1833 by the Walker party as they struggled through the
Sierra north of the Yosemite valley, the species did not attract popular
attention until its rediscovery in 1852, at what is now called the
Calaveras North Grove (see this
link for details). In the same year, specimens were received by Albert
Kellogg of the California Academy of Sciences, who in May 1855 finally
published it as Taxodium giganteum Kellogg and Behr. This was the
fifth validly published name, however. The first name had been assigned on
the basis of material collected (in the Calaveras grove) in summer 1853 by
William Lobb, who was directed to the tree by Kellogg. Lobb dashed back to
England, arriving 15 December 1853, and within two weeks the species was
published by botanist John Lindley as Wellingtonia gigantea, named
in honor of Arthur Wellesley, Duke of Wellington. In fact this name was
invalid, Wellingtonia having been described in 1840 for a plant in
the Sabiaceae, but this was not realized at the time. Lindley's
publication triggered a storm of protest from American botanists who were
outraged that the world's largest tree had been named for an English war
hero by a botanist who had never seen the tree. The Americans promptly
published a spate of invalid names. The French (always ready to irritate
the English) then intervened in the person of of Joseph Decaisne, who in
1854 published the species as Sequoia gigantea, a plausible
assignment that ultimately won acceptance by British botanists. Thereafter
Wellingtonia slowly disappeared from the literature. Unfortunately,
Sequoia gigantea was an invalid name, having been previously used
by Endlicher to describe a horticultural variety of the coast redwood, and
this problem was not satisfactorily resolved until the American John T.
Buchholz described Sequoiadendron in 1939. Buccholz' name was not a
popular choice, and was widely criticized by the old guard of California
botanists, but his arguments--based on substantial differences in the
development of Sequoia and Sequoiadendron seed cones--have
subsequently won general acceptance (Hartesveldt
et al. 1975).
Description
For the genus: "Trees giant, evergreen.
Branchlets terete. Leaves alternate, radiating. Adult leaves mostly
needlelike, triangular in cross section, somewhat divergent to strongly
appressed; abaxial glands absent. Pollen cones with 12-20 sporophylls,
each sporophyll with 2-5 pollen sacs. Seed cones maturing and opening in 2
years, persistent to 20 years, oblong; scales persistent, 25-45, valvate,
± peltate, thick and woody. Seeds 3-9 per scale, lenticular, subequally
2-winged; cotyledons (3-)4(-6). x = 11" (Watson
1993).
For the species: "Trees to 90 m; trunk
to 11 m diam.; crown conic and monopodial when young, narrowed and
somewhat rounded in age. Bark reddish brown, to ca. 60 cm thick, fibrous,
ridged and furrowed. Branches generally horizontal to downward-sweeping
with upturned ends. Leaves generally with stomates on both surfaces, the
free portion to ca. 15 mm. Pollen cones nearly globose to ovoid, 4-8 mm.
Seed cones 4-9 cm. Seeds 3-6 mm. 2n = 22" (Watson
1993).
Range
USA: California: at 900-2700 m in mixed
montane coniferous forests, in isolated groves along the western foothills
of the Sierra Nevada (Watson
1993). The species has been planted throughout Europe since 1853, and
is an especially popular ornamental in the U.K., where the largest
specimen (45 m tall and 260 cm dbh) grows at Leod Castle north of
Inverness (Hartesveldt
et al. 1975).
Big Tree
The General Sherman tree: height 83.6 m, dbh
825 cm, crown spread 33 m, located in Sequoia National Park, CA. This tree
also has the largest known stem volume, 1473.4 m3. The largest
diameter is recorded for the General Grant tree in Kings Canyon National
Park, CA, which is 885 cm dbh and 81.1 m tall. The second largest stem
volume, 1376.6 m3, is in the Washington tree, and the tenth
largest has a stem volume of approximately 1150 m3. It is
perhaps worth noting that timber scaling data show at least one specimen
of Sequoia
sempervirens logged in the early 20th Century had a recorded stem
volume of approximately 1540 m3 (Robert Van Pelt, e-mail,
29-Jul-1999). The tallest known giant sequoia is a specimen 93.6 m tall
measured Aug-1998 by Michael Taylor in the Redwood Mountain Grove,
California (Robert Van Pelt, telephone, 14-Nov-1998).
The giant sequoia is often called the
largest living thing on earth. That superlative is basically valid, but is
somewhat debatable for two reasons:
1. It is difficult to define "a single
living thing" among a group (living things) where it is sometimes
impossible to draw a clear line between the individual and the colony. For
example, an entire mountainside may be covered with a stand of aspen trees
(Populus tremuloides) that are genetically identical and physically
connected with each other (i.e., a clone); such a stand could be called
"a single living thing". Closer to home, taxonomically speaking,
clumps of Sequoia sempervirens may also be composed of genetically
identical stems. Even if we restrict the field to identifiable single
individual organisms, there are individuals of Ficus religiosa
reported from India and Southeast Asia that sprawl over areas of many
hectares; although a direct comparison has not been made, industrious
searching might turn up an individual larger than any Sequoiadendron.
At this time the largest documented Ficus that I have heard of, is
a banyan (F. benghalensis) in Uttar Pradesh, India, that supposedly
covers 2.1 ha (Robert Van Pelt, e-mail, 29-Jul-1999).
2. A large tree is not alive in the sense
that you or I are alive. The foliage and the outer surface of the tree
(technically, its inner bark, cambium and sapwood) are composed wholly or
in part of living cells. However, the bark and most of the wood (xylem)
are dead. In this sense a tree is a little bit like a coral -- we see the
living skin of tissue over a dead framework that the tree has built up
over the centuries of its growth. Most biologists overlook this point and
treat the entire tree, living tissue and dead wood, as "live
biomass." In practice, it is extremely difficult to measure how much
of a tree is actually living tissue, and I haven't heard of it being done
for any large trees. In conclusion, the General Sherman tree has the
largest stem volume and probably the largest total biomass of any known
individual tree. However, a few colonial organisms, including a variety of
plants and some fungi, may have greater cumulative living biomass.
Oldest
A specimen logged (long ago) in Converse Basin
was recently stump-counted at 3,266 years (Stephenson 2002). There are
also ages of 3,220 years (specimen D-21) and 3,075 years (specimen D-23)
collected by Andrew E. Douglass in 1919. These were stump counts (some of
Douglass' samples are still in storage at the Laboratory
of Tree-Ring Research; they weigh hundreds of pounds). Also, 3,033
years for specimen CMC3 collected by Swetnam and Baisan (Brown
1996). The only species (again, referring only to non-clonal
individuals) known to attain greater ages are Pinus
longaeva and Fitzroya
cupressoides.
Dendrochronology
Attracted early attention by Douglass and
others; most extensively studied by Tom Swetnam, Chris Baisan and
colleagues, who have assembled a very long fire history. They have a fine
web page describing this work, Fire
Regimes in Sierrian Mixed-Conifer Forests.
Ethnobotany
Observations
All wild Sequoiadendron groves are
protected, nearly all are on public lands, and most are relatively easy to
visit. Particularly impressive and accessible groves are found in
Yosemite, Sequoia and Kings Canyon National Parks; of these the most
popular, and among the largest, is the Giant Forest in Sequoia National
Park (Hartesveldt
et al. 1975). The President, shown here, can be seen on the Congress
Trail in the Giant Forest. It was originally (in 1923) called the Harding
Tree, an appellation that fell from popularity along with the late
President.
The genus is named for Sequoia, the
generic name of coast redwood, and the Greek DENDROS, tree (Watson
1993). The tree was discovered in 1833 by a hunter who happened to
wander into what is now the North Grove at Calaveras State Park; this has
since become the most-visited of all the groves, thanks to easy access (Flint
1987).
Although the giant sequoia has primarily
attracted attention due to its extremely large size, recent studies (Sillett
et al. 2000) have revealed that trees, like mountains, tend to
become structurally complex when they grow very large. A recent canopy
exploration of the second-largest tree, the Washington tree in Giant
Forest, found that the tree's canopy includes 46 secondary trunks, and
that the main trunk is hollow: a 35 meter deep, 2-3 meter wide pit extends
into the trunk below an entrance 58 m above the ground.
Redwood, including Sequoiadendron
giganteum and Sequoia sempervirens, is the state tree of
California (Watson
1993). |