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{{SPlantbox
{{SPlantbox
|familia=Cupressaceae
|familia=Cupressaceae
|genus=Sequoiadendron
|genus=Sequoiadendron
|species=giganteum
|species=giganteum
|common_name=Big tree, Giant sequoia, Sierra redwood
|common_name=Big tree, Giant sequoia, Sierra redwood
|name_ref=Flora - A Gardener's Encyclopedia
|name_ref=Flora - A Gardener's Encyclopedia
|usda_ref=Flora - A Gardener's Encyclopedia
|usda_ref=Flora - A Gardener's Encyclopedia
|max_zone=10
|max_zone=10
|image=Upload.png
|image=Sequoiadendron giganteum 08145.JPG
|image_width=240
|image_width=240
}}
}}
{{Two other uses|the species commonly called "giant sequoia"|the species commonly called "coast redwood"|Sequoia sempervirens|other uses|Sequoia}}
'''''Sequoiadendron giganteum''''' ('''giant sequoia''', '''Sierra redwood''', '''Sierran redwood''', or '''Wellingtonia''') is the sole living species in the genus '''''Sequoiadendron''''', and one of three species of [[conifer]]ous [[tree]]s known as [[Redwood (disambiguation)|redwoods]], classified in the family [[Cupressaceae]] in the subfamily [[Cupressaceae#Classification|Sequoioideae]], together with ''[[Sequoia sempervirens]]'' (Coast Redwood) and ''[[Metasequoia|Metasequoia glyptostroboides]]'' (Dawn Redwood). The common use of the name "sequoia" generally refers to ''Sequoiadendron,'' which occurs naturally only in the various groves that exist on the western slopes of the [[Sierra Nevada (U.S.)|Sierra Nevada]] Mountains of California.
[[File:Daniel Fuchs.CC-BY-SA.Sequoiadendron giganteum.jpg|left|thumb|Leaves of ''Sequoiadendron giganteum'']]
Giant Sequoias are the world's [[Largest organism|largest trees]] in terms of total [[volume]] (technically, only 7 living Giant Sequoia exceed the {{convert|42500|cuft|m3}} of the [[Lost Monarch (tree)|Lost Monarch]] Coast Redwood tree; see [[Sequoiadendron#Largest trees|Largest trees]]). They grow to an average height of 50–85 m (165–280 ft) and 6–8 m (18–24 ft) in diameter. Record trees have been measured to be 94.8 m (311 ft) in height and 17 m (57 ft) in diameter.<ref name="Flint 2002">{{Harvnb|Flint|2002}}</ref> The oldest known Giant Sequoia based on [[dendrochronology|ring count]] is 3,500 years old. Sequoia bark is fibrous, furrowed, and may be 90 cm (3 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 [[Conifer cone|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 [[seed]]s 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 seed is shed when the cone scales shrink during hot weather in late summer, but most seeds are liberated when the cone dries from fire heat or is damaged by insects (see ''Ecology'', below).
[[File:Seqgigcones.jpg|left|thumb|Giant sequoia cones.]]
Giant sequoia regenerates by seed. Trees up to about 20 years old may produce stump sprouts subsequent to injury. Giant sequoia of all ages may sprout from the [[Bole (botany)|bole]] when old branches are lost to fire or breakage, but (unlike coast redwood) mature trees do not sprout from cut stumps. Young trees start to bear cones at the age of 12 years.
At any given time, a large tree may be expected to have approximately 11,000 cones. The upper part of the crown of any mature Giant Sequoia invariably produces a greater abundance of cones than its lower portions. A mature giant sequoia has been estimated to disperse from 300,000-400,000 seeds per year. The winged seeds may be carried up to 180 m (600 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 m, but solitary trees will retain low branches.
Giant Sequoia is a very popular [[ornamental tree]] in many areas. ''Sequoiadendron'' has been successfully planted in the British Isles, parts of continental Europe, as well as in much of the western, southern, and eastern USA. Trees can withstand temperatures of −31 °C (−25 °F) or colder, for short periods of time providing the ground around the roots is insulated with either heavy snow or mulch. Outside its natural range, sequoia's foliage suffers from damaging windburn.
==Cultivation==
==Cultivation==
===Propagation===
===Propagation===
The giant sequoias are having difficulty reproducing in their original habitat (and very rarely reproduce in cultivation) due to the seeds only being able to grow successfully in mineral [[soil]]s in full sunlight, free from competing vegetation.
===Pests and diseases===
===Pests and diseases===
==Varieties==
==Varieties==
Since its discovery a wide range of [[cultivar|horticultural varieties]] have been selected, especially in Europe. There are, amongst others, weeping, variegated, pygmy, blue, grass green, and compact forms.<ref>[http://users.telenet.be/sequoiadendron/en/cultivars.html Overview of the horticultural varieties (cultivars) of the giant sequoia], telenet.be</ref>
==Gallery==
==Gallery==
<gallery perrow=5>
<gallery perrow=5>
Image:Upload.png| photo 1
Image:Grizzly_Giant_Mariposa_Grove.jpg| The "Grizzly Giant" tree
File:Sequoiadendron giganteum in Hungary.jpg| photo 2
File:Sequoiadendron giganteum 01 trunc by Line1.jpg| photo 3
</gallery>
</gallery>
