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How do coast redwoods become the tallest living trees?

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The massive Grizzly Giant sequoia tree stands with a wide, reddish-brown trunk and a hollowed base, surrounded by other tall trees in Mariposa Grove, Yosemite National Park. — Conifer A giant sequoia (*Sequoiadendron giganteum*) estimated to be between 1,900 and 2,400 years old, Grizzly Giant is the oldest tree in the Mariposa Grove, Yosemite National Park, California.

The coast redwood (Sequoia sempervirens) is the tallest living tree, with specimens exceeding 110 meters (350 feet) in height. These trees thrive in a narrow, humid coastal belt from southwestern Oregon to central California, where they are endemic to the region's fog belt.12

Their ability to reach such extreme heights is fundamentally linked to the cohesion theory of water transport. Because a vacuum pump cannot pull water beyond 10 meters, trees must employ a different mechanism to move water to their crowns. This process relies on transpiration, where water is pulled upward through the xylem along a gradient of decreasing pressure. For this to work, water molecules must hold together via cohesion and adhere to the walls of the xylem vessels. Despite the immense tension required to pull water to heights of 100 meters, the water columns within these trees are capable of withstanding the necessary pressure gradients without breaking.3