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Metasequoia glyptostroboides

Metasequoia glyptostroboides, the dawn redwood, is a fast-growing, endangered coniferous tree, the sole living species of the genus Metasequoia, one of three species in the subfamily Sequoioideae. It is native to the SichuanHubei region of China. Although shortest of the redwoods, it grows to at least 200 ft (61 m) in height.

Metasequoia glyptostroboides (dawn redwood) bonsai tree

Local villagers refer to the original tree from which most others derive as Shui-shan 水杉 or "water fir", which was part of a local shrine.[1]

History[edit]

In 1941 a forester named Kan, while performing a survey in Sichuan and Hubei provinces, happened across an enormous tree — as it turned out, an individual of Metasequoia — and recognized it to be special. In 1943, two more discoveries further brought Metasequoia to light: Chan Wang (1911–2000), a Chinese forestry official, also happened across an individual (said to have been the very tree that Kan had seen) and collected samples from it.[2] These samples were determined to belong to a tree as yet unknown to science. However, in the same year, a second discovery was made that ended up being supremely relevant: Shigeru Miki (1901–1974) of Kyoto University, studying fossil samples of the family Cupressaceae, isolated a divergent leaf form that led him to describe a new genus, which he named Metasequoia, meaning "like a sequoia." Only in 1946 was the connection made between Miki's new genus and the living samples identified by Kan and Wang.[2] Professor Hu Xiansu (1894–1968) is credited with making this important connection, and providing the specific epithet "glyptostroboides," after its resemblance to the Chinese swamp cypress (Glyptostrobus).[3]

Related species[edit]

Together with Sequoia sempervirens (Coast Redwood) and Sequoiadendron giganteum (Giant Sequoia) of California, M. glyptostroboides is classified in the subfamily Sequoioideae of the family Cupressaceae. Although it is the only living species in its genus, three fossil species are known as well. The other Sequoioideae and several other genera have been transferred from the Taxodiaceae to the Cupressaceae based on DNA analysis.[4]

Appearance[edit]

Dawn redwood foliage - note opposite arrangement
Pollen bearing cones
Young leaves
Young seed bearing cones
Mature seed bearing cones

While the bark and foliage are similar to another closely related genus of redwoods, Sequoia, M. glyptostroboides differs from the coast redwood in that it is deciduous, like Taxodium distichum (bald cypress). Similar to Taxodium, older trees may form wide buttresses on the lower trunk. Metasequoia is a fast-growing tree, exceeding 35 m (115 ft) in height and 1 m (3.3 ft) in trunk diameter by the age of 50, in cultivation (with the potential to grow to even greater dimensions). The trunk forms a distinctive "armpit" under each branch. The bark is vertically fissured and tends to exfoliate in ribbon-like strips.

The leaves are opposite, 1–3 cm (0.39–1.18 in) long, and bright fresh green, turning a foxy reddish brown in fall. The pollen cones are 5–6 mm (0.20–0.24 in) long, produced on long spikes in early spring; they are produced only on trees growing in regions with hot summers. The cones are globose to ovoid, 1.5–2.5 cm (0.59–0.98 in) in diameter with 16-28 scales arranged in opposite pairs in four rows, each pair at right angles to the adjacent pair; they mature in about 8–9 months after pollination.

Fossils[edit]

The genus Metasequoia was first described as a fossil from the Mesozoic Era by Shigeru Miki in 1941, but in 1943 a small stand of an unidentified tree was discovered in China in Modaoxi (presently, Moudao, Lichuan County, Hubei) by Zhan Wang;[5] due to World War II, these were not studied further until 1946 and only finally described as a new living species, M. glyptostroboides, in 1948 by Wan Chun Cheng and Hu Hsen Hsu. In 1948 the Arnold Arboretum of Harvard University funded an expedition to collect seeds and, soon after, distributed seeds and seedlings to various universities and arboreta worldwide for growth trials.

Conservation[edit]

In Lichuan, Hubei, there is a dawn redwood forest consisting of barely 5,000 trees[6] (by another count, around 5,400 trees.[7]), as well as a number of smaller groups (typically, under 30 trees each).[7] Since its discovery, the Dawn redwood has become something of a national point of pride, and it is both protected under Chinese law and planted widely.[6] However, it is still listed as endangered in the wild.[8] Though cutting of trees or branches is illegal, the demand for seedlings drives cone collection to the point that natural reproduction is no longer occurring in the Dawn redwood forest.[6] Although the species will continue to live in yards, parks and on roadsides all over China, the M. glyptostroboides forest ecosystem could disappear when its mature trees die.

Pizhou, Jiangsu boasts the Longest Dawn redwood avenue in the world. The avenue is approximately 60 km long with over one million trees.[9][10]

In 1995, the Crescent Ridge Dawn Redwoods Preserve was established in North Carolina. Here, hundreds of Dawn redwoods have been planted in a natural state where they can be observed and recorded in the wild, reducing the need for those in the U.S. to travel to China. The project goal is 1,000-5,000 trees. Currently, 200+ trees thrive in three separate groves. A fourth grove was lost to beaver depredation, and resulted in the loss of 125+ trees. CRDRP remains the only Eastern redwood forest in the U.S., and the sole wild Dawn redwood forest outside of China. The preserve is tentatively scheduled to open to the public in 2035.

Cultivation[edit]

Since the tree's rediscovery in 1943, the Dawn redwood has become a popular ornamental tree in parks and gardens worldwide. It has gained the Royal Horticultural Society's Award of Garden Merit.[11]

Dawn redwood has proved an easy tree to grow in temperate regions, and is now widely planted as an ornamental tree. Planted trees have already reached 25–40 m (82–131 ft) in height and 1–1.3 m (3.3–4.3 ft) in diameter, despite being in cultivation for less than sixty years. This rapid rate of growth has led to consideration for using the tree in forestry plantations. It has been discovered that M. glyptostroboides will thrive in standing water, much like Bald Cypress, and if left branched to the ground in full sun, will develop the large, contorted boles that have made it famous. Limbing or pruning at an early age will prohibit this formation later on.

In cultivation, M. glyptostroboides is hardy to USDA Zone 5, making it hardy down to lows of -25 °F (-32 °C). It is tolerant of soggy, waterlogged soils; in the wild it is adapted to growing on flood plains. Until it is established in a specific site, it is prone to drought and inadequate water availability. The Dawn redwood is recommended for urban areas in the Midwest, Southeast, and East Coast of North America, as its fast growth rate and tolerance for air pollution make it widely adaptable and able to thrive where other species might suffer. This species tends to struggle without irrigation in arid climates such as the American West unless planted directly on or adjacent to a body of water such as a pond or stream. This species is also highly susceptible to damage from contact with heavy amounts of winter de-icing salt.[12]

In the late 1980s, it was discovered that many of the second generation trees in cultivation suffered from inbreeding depression (extremely low genetic variability) which could lead to increased susceptibility to disease and reproductive failure. This was because most of the trees were grown from seeds and cuttings derived from as few as three trees that the Arnold Arboretum had used as its source. More widespread seed-collecting expeditions in China in the 1990s sought to resolve this problem and restore genetic diversity to cultivated M. glyptostroboides.

In the United Kingdom[edit]

The Dawn redwood can be found in some gardens of mansion houses and historic buildings. Bank Hall in Bretherton has two individuals believed to have been brought over many years ago from China and now under conservation protection. They are thought to have been a present from Kew Gardens in London to one of the families that lived at the hall. Nevill Hall Hospital, built on the grounds of a mansion, has a stand of ten trees planted adjacent to the Pathology Laboratory. Three trees are at Croxteth Hall in Liverpool. There are also trees on the grounds of Askham Bryan College (York), the Arboretum Trust (York), Dulwich Picture Gallery (South London), and Hyde Park (London) - at the eastern end of the Serpentine Lake, described by its plaque as a Water Fir. Cambridge University Botanic Garden has at least two tall dawn redwood trees, which were planted in 1949 and at the grounds of least one Cambridge college harbour a dawn redwood (Downing college). There are two specimens growing in Belle Vue Park, Newport City, South Wales, UK, not far from Neville Hall Hospital above. One specimen is on the grounds of Pinderfields Hospital, Wakefield.

In the United States[edit]

Dawn redwoods thrive over a large, crescent-shaped region that encompasses the eastern and southern United States. Many institutions, such as the Arnold Arboretum of Harvard University have fine specimens, but the Crescent Ridge Dawn Redwoods Preserve in North Carolina remains the only endeavor for the re-introduction of the species into a natural setting in the US.

See also[edit]


A Dawn Redwood specimen located at Croxteth Hall in Liverpool.

References[edit]

  1. ^ Bartholomew, Bruce, D. E. Boufford, and S. A. Spongberg. "Metasequoia glyptostroboides--Its present status in central China." Journal of the Arnold Arboretum 64.1 (1983): 105-128.
  2. ^ a b Ma, Jinshuang (2003). "The chronology of the "living fossil" Metasequoia glyptostroboides (Taxodiaceae): A review (1943–2003)". Harvard Papers in Botany 8 (1): 9–18. Retrieved 22 March 2014. 
  3. ^ "Crescent Ridge_History". 
  4. ^ Gadek, P.A., Alpers, D.L., Heslewood, M.M., and Quinn, C.J. (2000). Relationships within Cupressaceae sensu lato: A combined morphological and molecular approach. American Journal of Botany, 87(7): 1044-1057.
  5. ^ Ma, Jinshuang; Shao, Guofan (2003). "Rediscovery of the 'first collection' of the 'Living Fossill', Metasequoia glyptostroboides". Taxon 52 (3): 585–8. doi:10.2307/3647458. 
  6. ^ a b c Save The Redwoods League, Fall Bulletin, 1999, PDF 2.7 MB
  7. ^ a b Langlois, Gaytha A. (2005). "A conservation plan for Metasequoia in China". In LePage, Ben A.; Williams, Christopher James; Yang, Hong. The geobiology and ecology of Metasequoia. Volume 22 of Topics in geobiology. Springer. p. 369. ISBN 1-4020-2631-5. 
  8. ^ Farjon, A. (2010). "Metasequoia glyptostroboides". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 2013-12-11.  Listed as Endangered B1ab(iii,v), v3.1
  9. ^ The Creation of the Longest Avenue in The World, Arboricultural Journal: The International Journal of Urban Forestry, 2013.
  10. ^ The Longest Avenue, The Horticulturalist: The Journal of the Institute of Horticulture, 2013.
  11. ^ "RHS Plant Selector - Metasequoia glyptostroboides". Retrieved 24 May 2013. 
  12. ^ Dirr, M.A. 1998. Manual of Woody Landscape Plants. Stipes Publishing Co., Champaign, IL. (1453 p.)

Further reading[edit]

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