By Mary Yee, contributor
Imagine going on a hike in the woods and suddenly coming upon a live dinosaur in a clearing. The botanical equivalent of this improbable event occurred in a remote corner of central China in 1941. In the village of Modaoxi in Hubei province, forester Gan Duo came upon a large tree he was unable to identify. Because the tree had already shed its leaves by that time of the year, Gan asked a local school principal to collect branches and seeds the following season. Whether those collections were ever made is not clear, but the principal, Yang Lung Tsing, became interested in the tree.
In 1943, Yang met up with a former classmate who had come to central China to survey the forests and asked him, Professor Zhan Wang of the Agricultural College in Beijing, to help identify the unusual tree. Zhan agreed to have a look and found that the tree resembled the Chinese swamp cypress. However, its leaves and cones were clearly not the same as the well-known cypress.
Zhan collected branches and cones from the mature tree he encountered in Modaoxi and studied them when he returned from the field. However, as China was at war during this period, he was unable to access the references that might have helped him identify the tree. In 1945, he showed the collected plant material to Professor Zheng Wanjun, a conifer specialist at the National Central University in Nanjing. Intrigued by what he saw, Professor Zheng decided that more research was needed and sent one of his students, Xue Jiru, to Modaoxi to collect additional samples from the tree. Later in life, Xue wrote an account of his journey through the mountainous, sparsely populated area where bandits were known to prey on travelers. The tree was very tall and Xue had to throw rocks at the branches to bring down some of them, along with cones containing seeds. He made it safely back to Nanjing with his quarry.
Professor Zheng shared the specimens with Professor Hu Xiansu of the Fan Memorial Institute of Biology in Beijing. Professor Hu had received his degrees from the University of California at Berkeley and Harvard University. Despite the war between China and Japan, he had access to international scientific journals and had read a paper by Japanese paleobotanist Shigeru Miki describing a tree found in the fossil record in Japan. Because of the tree’s similarity to American redwoods or sequoias, Dr. Miki named the fossil tree “Metasequoia”, meaning “like a sequoia”. Professor Hu recognized the specimens he had on hand as identical to those in the fossil record. In 1948, he and Professor Zheng of Nanjing jointly published their identification of this “living fossil tree.” Following Dr. Miki’s lead, they named it “Metasequoia glyptostrobus”.
With funding from Harvard University’s Arnold Arboretum, the Chinese professors organized another expedition to Modaoxi to collect seeds from all the Metasequoias that could be found in the vicinity. The seeds were distributed to botanical gardens in Asia, Europe and the United States. The germination rate was high and many of the seedlings have now become mature trees in public gardens across the world.
When botanist Ralph Chaney at Berkeley heard about this tree’s discovery, he was determined to visit China and see for himself. With funding from the Save the Redwoods League, he made the trip in 1948 when civil war was still raging between the Chinese nationalist and communist factions. He was accompanied by Milton Silverman, science writer for the San Francisco Chronicle. Searching for a smaller mouthful than Metasequoia glyptostrobus, Silverman, with his editor, coined the common name for this new tree: dawn redwood. The Chronicle subsequently trumpeted that “Dr. Chaney brought the tree back to America after a 250 million years absence.”
Why “back to America”? It turns out that eons ago, Metasequoia grew not only in China and Japan but also in North America. Its fossils have been found all over Canada and, in the U.S., from Oregon to North Dakota. Scientists have speculated about the turns of fortune that reduced the widespread distribution of this tree to a small, isolated population in central China. There was a very real fear that this tree could become extinct because of human pressure on its habitat.
Fortunately, the dawn redwood has proven to be a resilient relic and easy to grow. It is readily propagated in nurseries and is now widely planted as an ornamental tree in temperate zones all around the world. Many trees were planted in the wake of its discovery thanks to popular interest in this “botanical dinosaur”. In America the common name dawn redwood has caught on.
The dawn redwood is a true conifer, with needled leaves and seeds hidden in cones. However, unlike its closest relative, the American redwood, the dawn redwood is deciduous, not evergreen. Like its more distant American cousins, the bald cypress and the larch, its needles change color and are shed in autumn. It grows quite fast and can easily reach 70 feet in height. Some of the trees grown from the 1948 seeds are now 90 to 100 feet tall. The dawn redwood is conical in shape and the base thickens as the tree matures, making for a majestic silhouette.
I first encountered this tree in the conifer collection at the National Arboretum in Washington DC. As a research institution, the Arboretum received seeds from the 1948 collection and had a grove of well-established trees by the early 1990’s. When I moved to Minnesota in 1999, I looked for this tree in local botanical gardens and learned it was not considered hardy in this area. However, more recently, I found a single dawn redwood growing robustly in a Wisconsin garden with low temperatures equal to those of the Twin Cities. It may be that 20 to 30 million years after it disappeared from the fossil record in the American Midwest, the dawn redwood will once again grace our landscapes here.