The Giant redwood goes by many names and it is one of the most well known trees throughout the world. They are the largest tree by mass - but not the tallest - that title goes to the Coastal redwood. In Exeter there are a few Giant redwood trees and they are easy to spot. There is a medium sized one on Dix's field which is within the city centre boundary and also a slightly smaller one at Pinces Gardens. There is also a good sized specimen in Rougemount gardens which is near the library in the city centre. Due to the huge sizes that these trees can grow to they require a large amount of space.
The Giant redwood is native to California. They grow naturally in groves on the western slopes of the Sierra Nevada Mountains of California. Due to the huge amount of interest these great trees cause they have been widely planted across the world. They were first introduced to the UK in the 1850's and were planted in many private estates and suitable sized grounds. The naming of the tree caused quite a few problems which is why in some parts of the world it goes by a different name. There was a bit of a race to name the tree which is why some people call it 'Washingtonia gigantea' and others refer to it as 'Wellingtonia gigantea'.  The agreed scientific name is ​'Sequoiadendron giganteum'. The  most common names used are Giant redwood, giant sequoia or simply big tree.
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Even at a young age they can easily be tallest tree in the area
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The bark is dense and soft and reddish in colour
The lifespan of these trees are equally as large - up to 3000 years! If you come across a large Giant redwood in the UK it's only going to be 100 to 150 years old based on the fact they were only introduced in the 1850's. They can grow to an average height of 50–85 m and the trunk diameters can range from from 6–8 m. Simply put - these trees are massive. Record trees have been measured at 94.8 m in height and ​trunk diameters of 17 m. They are also the fastest growing conifer on earth given the right conditions and can grow 1.2m per year. During their younger years they grow rapidly tall and less dense when the rising and setting sun is blocked. When they reach full sun they stop growing as rapidly tall and start putting their growth into their trunk and foliage.
The male flowers are yellow and on the tips of the leaves
The leaves are evergreen and are awl-shaped, 3–6 mm (1⁄8–1⁄4 in) long
It is monoecious in nature which means the male cones (pollen bearing) and the female cones (seed bearing) are on the same tree but different parts. On mature trees there can be as many as 11,000 cones and each cone can release anything from 14 to 24 seeds via the wind or rain. With this in mind they can easily release 250,000 or more seeds from the mature female cones. However, only 5% of the seeds will germinate and even fewer will actually grow into saplings. Giant redwood can only reproduce from seed whereas the Coastal redwood can reproduce via seeds and suckers. Interestingly the Giant redwood can start making viable seed from as young as 5 years of age although usually it's around 10 years. In their natural habitat forest fires play an important in role is assisting seed germination and clearing out any competitive vegetation.  Both the sap and the bark have a high tannin content which aid with fire resistance. The bark is soft and fibrous and if you were to hit it with your hand it wouldn't really hurt. Also the thickness of this soft and cushion like bark is quite deep - up to 60cm. 
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The canopy has many branches and twigs
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The mature female cones are 1 to 1.5 inches in size
The leaves are evergreen and are awl-shaped, 3–6 mm (1⁄8–1⁄4 in) long, and arranged spirally on the shoots. The trees that I have studied in Exeter seem to flower during February to March although in their natural range it might be earlier. The male bearing cones appear as  yellowish-brown tufts at the end of the leaves throughout the tree. The female cones are harder to spot as they are green and tend to be on the upper branches. Over time they mature into solid brown cones which are around 1 to 1.5 inches in diameter. 
OTHER USEFUL LINKS
QUICK FACTS
  • It was first introduced into the UK in the 1850's
  • They grow naturally in groves on the western slopes of the Sierra Nevada Mountains of California
  • Is the sole living species in the genus Sequoiadendron and one of three species of coniferous trees known as redwoods
  • The three types of Redwood are Giant redwood, Coastal redwood and Dawn redwood
  • The oldest known Giant redwood is 3,200-3,266 years old
  • They are the most massive individual trees in the world
  • They grow to an average height of 50–85 m but some trees have been measured at 94.8 m
  • The diameter of the trunk can be as large as 17 m
  • They are fast growing trees and grow as much as 1.2m per year (in their young years)
  • The leaves are evergreen and awl-shaped and around 3–6 mm in length
  • They are monoecious so the male and female cones are on the same tree but different parts
  • Flowering usually occurs in late autumn to early spring
  • The male cones are yellow and easier to spot than the female cones which are green
  • A mature tree can have up to 11,000 mature cones present
  • Each cone can contains anything from 14 to 24 seeds
  • Over 250,000 seeds can be released each year but as little as 5% will germinate
  • Sadly they are now on the endangered species list due to habitat loss, logging and air pollution
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