Roots

Elizabeth Royte is unsure who The Tree was written for but she thoroughly enjoyed this homage
to our leafy friends

the tree

By Colin Tudge

Illustrated

Crown Publishers

€29.80

In the early 1900s, fruit and walnut growers ripened their harvest in sheds warmed with kerosene stoves. Eventually, forwardlooking orchardists switched to electricity, which was cleaner and more reliable. But electric heating had an insurmountable drawback. It turns out it wasn't warmth that had been doing the ripening, but the ethylene leaking from the smelly old heaters. Scientists now know that ethylene, a derivative of petroleum and natural gas, is also emitted – as a hormone – by plants. Ethylene causes fruit to ripen, and leaves and fruit to drop. Commercial growers use it to thin crops of plums and peaches (so the remaining fruits grow bigger) and to loosen berries in preparation for mechanical harvesting .

"So it is that plants control their form," Colin Tudge writes in The Tree: A Natural History of What Trees Are, How They Live, and Why They Matter. The subtitle is as straightforward as can be, but the book is oddly more – a descriptive catalogue of all the trees in the world in which Tudge expounds on how many there are in each family, where they grow, their physical characteristics, why they are ecologically or economically important and the tasty details of their sex lives.

But this book isn't useful as a guide: its illustrations are few and there are no keys. It is written as a tribute to the world's 60,000 species but it's hard to say for whom it is intended. Maybe someone like me, who has a thing for trees, forgets her botany, marvels at what basic science has revealed and turns a sympathetic ear toward humanistic prescriptions for saving the earth.

Like most biographies of objects, this one presents its subjects as essential players on the global stage. Without trees, Tudge says, we wouldn't be here. They helped form our atmosphere (without photosynthesis there would be no oxygen), they may have helped shape us (we may partly owe our big brain and dexterous hands to millions of years in the trees), they feed and shelter us and they provide invaluable ecosystem services, like flood control.

Most people appreciate trees for their beauty and awesome utility, but Tudge wants us to know there's more to it, that it's hard out there on a pine. Trees must compete every second for "water, nutrients, light and space; and to fend off cold, heat, drought, flood, toxicity and the host of parasites and predators of all conceivable kinds", he writes. In perpetual dialogue with all that surrounds them, trees "gauge what's going on as much as they need to, and they conduct their affairs as adroitly as any military strategist". How? By growing toward light; concocting chemical deterrents to pests from raw materials they take from the air, water and soil; thickening their trunks in response to stress; and attracting their animal collaborators when it's time to reproduce.

Tudge, the author of Global Ecology and other books, writes simply and with unapologetic enthusiasm. He also has a sense of humor. Pandas were once carnivorous, he says, but they now limit themselves to bamboo. "Though if you want to catch a panda, lure it into a [bamboo] cage with roast pork. It's the same with all vegetarians."

There are dozens of 'wow' and 'who knew?' moments throughout, until the book, in its final section, takes a sudden and uncompromising political turn. Thanks to all of us, the earth's climate is rapidly warming, and trees can't evolve fast enough to cope with the changes. What to do? Turn away from current development models, which focus on industrialisation and will continue to pump out carbon dioxide, Tudge says, and support grassroots arbo-centric economies.

Tudge calls for a new type of governance, one that takes account of the "realities of soil, water and climate" and the needs of humanity at large. Despite sometimes slipping into vagueness, Tudge is courageous to take this stand and risk alienating readers who have stuck with him throughout solely for the love of trees and his enchanting way of writing about them.

(Elizabeth Royte's most recent book, Garbage Land: On the Secret Trail of Trash, has just been published in paperback