GRAND (Meredith): My favourite tree in Hamilton… She (she? Seems right somehow) stands alone at one edge of the large rhododendron lawn at Hamilton Gardens: a grand old lady, yet an unassuming one. She dwarfs the trees and shrubs around the border of the lawn, in that straggly, reach-for-the-sky-without-quite-meaning-to way that eucalyptus have. Her lower trunk is covered with etched initials, but it’s the higher branches that draw me in – the peeling bark and the hyper-smooth surfaces revealed as it falls away.
When I see a tall tree, I can’t help but visualise its plumbing – the way the water is pulled upwards, in an unbroken chain, from roots, up the xylem in the trunk, to branches and ultimately leaves. The continuity of the water is crucial – without that, there’s no way the water can thwart gravity to move up, up, up to the highest leaves. It’s all made possible by the powerful hydrogen bonds between individual water molecules.
A 2004 study (BBC synopsis here) looked at the theoretical maximum height of a tree, and particularly at how tall a continuous thin tube of water (the plumbing) could get before it disintegrates. Remarkably, the authors found that the tallest of the California redwoods (including the then tallest of all at 112.7 m) get damn close to their calculated maximum of 130 m. ‘My’ tree is several times smaller – 25 m is a generous guess – but it’s a wonder of engineering no less, and a thing of gentle beauty.
through a science lens 