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China's Living Fossil
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17314 |
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Section : |
NATURAL SCIENCE
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| Issue
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2 / 1990 |
1,014 Words |
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John Kuser
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Imagine how you would feel if you were exploring a remote valley halfway around the world and suddenly saw a live dinosaur.
A similar feeling may have swept over a Chinese forester named Gan Duo in 1941, when he came across a peculiar deciduous tree called shuisha by the people of Wanxian district in western China. The tree was identified by the director of the Fan Memorial Institute in Beijing as belonging to the same genus as redwood like fossils described in a 1941 Japanese paper establishing a new fossil genus, Metasequoia. Since then, redwood fossils from China, Japan, and the United States to Greenland, Iceland, and the far northern territory of Spitsbergen have been identified as Metasequoia glyptostroboides. The youngest of these fossil specimens are thought to be 13-20 million years old.
The present natural range of metasequoia is restricted to a small area in west-central China near the upper reaches of the Yangtze River, within the provinces of Sichuan, Hunan, and Hubei. In its natural range the tree is found at altitudes between 750 and 1,500 meters in acidic yellow soils with moderate climate and abundant summer rainfall. Preferred sites are damp mountain slopes and ravines, and it is often cultivated along riversides and near the borders of rice paddies.
In 1946, when Elmer Merrill of the Arnold Arboretum in Jamaica Plain, Massachusetts, received botanical specimens of metasequoia, he immediately became interested in the possibility of securing seeds of this extraordinary species. He was able to arrange a modest grant and organized a seed-gathering expedition to China, where about one kilogram of seeds was collected. In keeping with a long-established practice of the arboretum, Merrill distributed some 600 packages of the seeds free to 76 institutions and persons in the United States and Europe.
After the initial distribution of metasequoia seed in the Western world, it soon became obvious that the "living fossil" was well adapted to many parts of the temperate zones and capable of growing as much as six feet a year in favorable circumstances. Young metasequoias flourished in the summer rainfall climate of the eastern United States and, where given enough water, they grew along the Pacific coast from southern California to British Columbia. They did so well in England that in 1977 and 1982, the Forestry Commission published lists of Britain's largest specimens. In 1982, the Arnold Arboretum likewise published a list of 50 of the largest ones in the United States, Canada, England, and New Zealand.
The species requires full sunlight for best growth and shows a decided preference for streamside sites similar to those it occupies in China. Metasequoia has become a handsome, popular ornamental tree in the parts of the United States where it thrives. Its three principal landscape uses are for individual accent trees, naturalistic groves, and closely planted avenues of trees called allées. Metasequoia's values as a landscape tree are its rapid growth, symmetrical conical shape, feathery light-green foliage which keeps growing until August or September, coppery fall color, tassellike male catkins which develop on larger trees, and cedarlike bark.
Because of its family relationship with coast redwood, Sequoia sempervirens, and even closer relationship to the southern bald cypress, Taxodium distichum, it was thought
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