20. Sequoiadendron giganteum
Wellingtonia or giant redwood is the largest single stem tree and the largest living thing (by volume) on earth. The tallest was measured at 94.8 metres (311 feet). This one is around 23 metres (75 feet) tall. The largest measured diameter is 8.2 metres (27 feet). They can live up to 3500 years. The bark can be up to 1 metre (3 feet) thick and is unusually fire resistant. They require fire to reproduce as the cones open after being exposed to heat and the seeds can germinate when excess vegetation has been burnt on the ground. The main economic uses are tourism and horticulture.