The Giant Sequoia tree is the largest living plant on the planet, growing to about 300 feet (92 metres) tall. An adult tree is over 30 feet (9 metres) wide, and it takes 7-20 people to encircle it. It weighs more than 649 tons, equal to 107 elephants. It can live to be 3,000 years old. So, how does such a tiny seed grow into the largest living tree on earth?
The wild learning adventure team at Calaveras Big Trees State Park and the Jonsteen Nursery in California in America jointly presented a virtual lesson on 6 April 2021 on the Giant Sequoia tree. They presented information on the lifecycle of the tree in nature and in a nursery greenhouse setting.
The Giant Sequoia (Sequoiadendron giganteum) in the Cupressaceae family of cypress trees, is the State tree of California because it is native to the region. It is also known as the Giant Redwood. It likes to live in a mixed conifer forest (cone-bearing trees). The leaves are evergreen. The seed cones are about 3 inches (7 centimetres) long.
There are many challenges on its lifecycle from seed to giant tree. The cone can remain green for many years, often up to 20 years. Each cone has spirals with contain seeds – on average 230 seeds per cone. One tree can have as many as 11,000 cones.
For such a large tree, the cones are small – about the size of a cone of a regular conifer tree. Each seed is the size of an oatmeal.
The Giant Sequoia can only grow if the seed leaves the cone. It needs heat or fire to open up the cone to release the seeds (the heat needs to be 85 degrees Fahrenheit or 29 degrees Celsius). This means that the Giant Sequoia is serotinous – remaining closed on the tree with seed dissemination delayed or occurring gradually.The process of opening is called serotiny.
Ash from fire is nature’s fertilizer, but it also needs a lot of water – up to 500-600 gallons (2,273-2,727 litres) of water a day. Water triggers the growth of the seeds.
Scientists think that only one seed in a million seeds grows to a full adult tree. Hence, the Giant Sequoia trees doesn’t grow easily in nature. It also needs the space to grow.
The Jonsteen Nursery in California Plant collects the cones and seeds. It amplifies the process of growth in nurturing the seeds and seedlings.
The Giant Sequoia tree was identified in the Sierra Nevada of California in 1833 and introduced into Europe in 1860. In the Luxembourg Gardens in Paris, France, there are two Giant Sequoias (photographed below in April 2021), currently at 130 feet (40 metres) tall – half their expected height. Visitors will notice its thick, fibrous reddish-brown bark that can withstand fires and cold.
Photographer: Calaveras Big Trees State Park and the Jonsteen Company; and Martina Nicolls