Science writer Richard Preston talks about some of the most enormous living beings on the planet, the giant trees of the US Pacific Northwest. Growing from a tiny seed, they support vast ecosystems — and are still, largely, a mystery.

The tallest tree in the world is a Sequoia sempervirens, the Hyperion Tree. A Redwood tree 115.61 meters tall (379.3 ft).

The largest tree in the world, by volume, is a Sequoiadendron giganteum, the General Sherman Tree. With a height of 83.8 metres (275 ft), a diameter of 7.7 meters (25 ft), with an estimated bole volume of 1,487 cubic meters (52,513 cu ft), and an estimated age of 2,300–2,700 years.