written by: Henri Nielsen•edited by: Paul Arnold•updated: 1/13/2012
The dawn redwood was believed extinct until Chinese refugees fleeing the Japanese WWII invasion came across several growing in remote villages of western China.
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The story of the dawn redwood is most fascinating, because its discovery and subsequent identification occurred in a WWII war zone and involved scientists from both sides of the conflict. China serves as the backdrop for this story, but it is important to note that if the tree had not been found for another few years, international cooperation would have been impossible because of the rise of Mao Tse-tung and the subsequent isolation of the populous country.
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The Fossil Record
Up until the 1940s, the dawn redwood was only known through the fossil record that it left behind on exposed slabs of rocks and as pieces of petrified wood. First noticed by the scientific community in the mid 19th century, the conifer was originally classified in the same family and genus as the bald cypress. From its fossilized remains, it was ascertained that the tree first appeared on the planet about 90 million years ago during the Cretaceous era. The towering plant reached its prime about 50 million years ago during the Eocene era when the tall pyramid-shaped tree grew abundantly all across North America, Asia and Northern Europe.
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Around 1940, the dawn redwood became scientific news, when a Japanese paleobotanist, Shigeru Miki, reclassified the fossil plant into a new genus that he named Metasequoia. This taxonomical correction was based on the observation that the fossilized samples had opposite attachment of the leaf stems, instead of the usual alternate arrangement, which is present among the bald cypress and the California redwood.
No sooner had Miki, a professor of botany at Osaka City University released his findings than a Chinese forester, Tsang Wang, chanced upon a strange deciduous conifer growing in a remote village in the Szechuan province of China. The year was 1941 and the unique discovery came as well-to-do Chinese aristocrats searched remote areas of Western China for a retreat from the Japanese invasion. However, accurate scientific identification of this graceful and deciduous conifer that the locals called the Water Fir would not occur for another few years.
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The Search For Viable Seeds
With some financial support from the US, Hu and his associates collected seeds and sent them to the Arnold Arboretum, located on the Harvard campus in Cambridge, Massachusetts. Hu also supplied botanists within his own country with seed samples from the dawn redwood. From the US, the seed stock was spread to Denmark, England, the Netherlands and India, as well as many places within the United States. Soon botanists and horticulturists would be learning if the new tree could be successfully cultivated in other parts of the world.
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Even before the war ended, a small circle of Chinese scientists had become fascinated by the tall, deciduous conifers found in the Szechuan province. At first, the Chinese forester thought he had found samples of a Chinese Swamp Cypress, but nonetheless, in 1943 samples of the tree were sent to two Chinese botanists, Chung-Lun Wu and Wan-Chun Cheng who worked and lived in close proximity to the original site in western China.
The two scientists soon realized that their botanical evidence was not from any known living tree and so samples of the plant eventually ended up in Beijing in the hands of Hsen-Hsu Hu, a well-known botanist who had studied at Harvard University and was employed at the Fan Memorial Institute of Biology, in Bjeing.
In 1946 Hu matched the samples with the fossil record of the plants studied by the Japanese paleontologist and realized that he had in his possession the same tree that had been showing up in the fossil record for many years. Now, it became apparent that a tree once thought wiped off the face of the planet was now growing in a remote area of western China.
Right away, he notified Dr. E. D. Merrill, his old teacher at the Arnold Arboretum in Harvard. At the same time he also sent some leaf samples of the tree. The Harvard botanist agreed with Hu on his findings and the name of Metasequoia glyptostroboides was given to the newly discovered tree.
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Grow Your Own
Fortunately, seeds from China were viable and turned out to be fairly easy to grow. Dawn redwood trees planted in wet, temperate climates such as New England, Denmark and Great Britain still survive today as healthy specimens. At present (2011), seeds or cuttings are available to home owners and gardeners from numerous nurseries and landscapers located in many countries including the U.S.
Since the tree is naturally pest and disease resistant, it has become a popular ornamental that takes well to full sun and well-drained, slightly acidic soil. The dawn redwood is fast growing and capable of reaching a height of 100 feet, if conditions are right. The feathery foliage gives the tree a graceful appearance during the growing season, followed by a beautiful golden brown autumn color that occurs before the needles drop. The tree has shown remarkable resistance to overly wet and dry growing conditions, but some considerations to winter cold must be taken into account. The dawn redwood grows best in USDA hardiness zones 5 - 9.
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Status Of the Dawn Redwood Today
Botanical expeditions to China have revealed a wider range of trees than originally thought, but still the best estimates suggest that only about a thousand trees are surviving in the wild. Although not endangered as an ornamental plant, dawn redwoods growing wild in China are under severe pressure from agricultural expansion and it is highly questionable whether the tree will be able to retain its natural ecological niche.