Hope Jahren on encountering a living fossil.
If you head north, far above the Arctic Circle, you will find yourself in a land of blue sky, white snow, and gray ice. There will be pockets, here and there—a lonely island, a sloping valley—that are dry, dusty, and desolate. Dig down, through a crust of lichens, take out the smooth stones underneath, and burrow into the shaley, ancient mud. When you get to layers no less than forty million years old, you will find conifer needles. Not only that, you will find twigs, branches, cones, and even whole trunks, dusted in ancient sap. I have seen this myself, during the odd, dream-like hours that are born of twenty-four-hour light.
Forty-five million years ago, at 79° north latitude, an immense conifer forest stretched in every direction, across what is now Canada, Alaska, and Siberia, quite close to today’s North Pole. The idea of a forest so far north is nothing short of fantastic: today, the tallest plant in the region is a pussy willow—and a stunted specimen at that. The temperature and the rainfall above the Arctic Circle were certainly very different forty million years ago. Still, one thing has not changed: total light for three months, soon followed by three months of total darkness. No modern trees can tolerate these conditions, yet forests once thrived under this ridiculous annual regime. Foremost among the trees was Metasequoia. We recognize them from their needles—fossilized but so loose that they fall through your fingers like confetti.
Until 1948, most scientists assumed that Metasequoia was extinct, based on fossils from lower latitudes. That was the year the Arnold Arboretum received a package from Hu Xiansu, who trained at the Arboretum and returned to China with his doctorate in 1925. Hu sent bushels of seeds and other botanical materials, and he documented that they had come from—wait for it—live Metasequoia glyptostroboides growing in central China! Some of these seeds became the full-grown, magnificent “dawn redwoods” that now stand throughout the Arboretum (accessions 3-48 and 524-48).
Because of these seeds and the trees they became, I knew something about the fossils that we excavated in Canada that I would never have known otherwise: ancient Metasequoia trees were deciduous. Deciduousness is a special type of dormancy meant to decrease the stress of maintaining leaves through the winter. This trait, uncommon in conifers, would make all the difference as the trees prepared for the extended Arctic darkness.
Hope Jahren’s most recent book, The Story of More: How We Got to Climate Change and Where to Go from Here, was published in 2020.
From “free” to “friend”…
Established in 1911 as the Bulletin of Popular Information, Arnoldia has long been a definitive forum for conversations about temperate woody plants and their landscapes. In 2022, we rolled out a new vision for the magazine as a vigorous forum for tales of plant exploration, behind-the-scenes glimpses of botanical research, and deep dives into the history of gardens, landscapes, and science. The new Arnoldia includes poetry, visual art, and literary essays, following the human imagination wherever it entangles with trees.
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