dawn redwood

Metasequoia Fossil range: 70.0–0 Ma PreЄ Є O S D C P T J K Pg N Late Cretaceous to recent
Conservation status
Critically Endangered (IUCN 2.3)
Scientific classification
Kingdom:	Plantae
Division:	Pinophyta
Class:	Pinopsida
Order:	Pinales
Family:	Cupressaceae
Subfamily:	Sequoioideae
Genus:	Metasequoia Miki, 1941
Species
†Metasequoia foxii Metasequoia glyptostroboides †Metasequoia milleri †Metasequoia occidentalis

Metasequoia (Dawn Redwood) is a fast-growing, deciduous tree, and the sole living species, Metasequoia glyptostroboides, is one of three species of conifers known as redwoods. It is native to the Sichuan-Hubei region of China. Although shortest of the redwoods, it grows to at least 200 feet (60 meters) in height. Local villagers refer to the original tree from which most others derive as Shui-sa, or "water fir," which is part of a local shrine. Since that tree's rediscovery in 1944, the Dawn Redwood has become a popular ornamental.

Together with Sequoia sempervirens (Coast Redwood) and Sequoiadendron giganteum (Giant Sequoia) of California, Metasequoia is classified in the Cupressaceae subfamily Sequoioideae. Although M. glyptostroboides 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 former Taxodiaceae family to Cupressaceae based on DNA analysis.^[1]

Paleontology

Metasequoia redwood fossils are known from many areas in the Northern Hemisphere; more than twenty fossil species have been named (some were even identified as the genus Sequoia), but are considered as just three species, M. foxii, M. milleri, and M. occidentalis (Farjon 2005). During the Paleocene-Eocene Thermal Maximum, extensive forests of Metasequoia occurred as far north as Axel Heiberg Island^[2] (northern Canada) at around 80°N latitude. Large petrified trunks and stumps of the extinct Metasequoia occidentalis (sometimes identified as Sequoia occidentalis) also make up the major portion of Tertiary fossil plant material in the badlands of western North Dakota in the United States.

The trees are well known from late Cretaceous to Miocene strata, but no fossils are known after that. Before its discovery, the taxon was believed to have become extinct during the Miocene; when it was discovered extant, it was heralded as a "living fossil".

Appearance

Dawn Redwood foliage - note opposite arrangement

Male cones

Mature female cones

Young leaves

While the bark and foliage are similar to another closely related redwood genus Sequoia, Metasequoia differs from the California redwood in that it is deciduous like Taxodium distichum (Bald Cypress), and like that species, older specimens form wide buttresses on the lower trunk. It is a fast-growing tree to 40-45 m tall and 2 m trunk diameter in cultivation so far (with the potential to grow to even greater heights).

The leaves are opposite, 1-3 cm long, and bright fresh green, turning a foxy red-brown in fall. The pollen cones are 5-6 mm long, produced on long spikes in early spring; they are only produced on trees growing in regions with hot summers. The cones are globose to ovoid, 1.5-2.5 cm 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.

Metasequoia was first described as a fossil from the Mesozoic Era by Shigeru Miki in 1941, but in 1944 a small stand of an unidentified tree was discovered in China in Modaoxi by Zhan Wang; due to World War II, these were not studied further until 1946 and only finally described as a new living species of Metasequoia in 1948 by Wan Chun Cheng and Hu Hsen Hsu. In 1948 the Arnold Arboretum of Harvard University sent an expedition to collect seeds and, soon after, seedling trees were distributed to various universities and arboreta worldwide for growth trials.

See also

Sequoioideae:

Displaying autumn foliage in Victoria, BC, Canada

The trunk of an adult tree

The base of the trunk.

References

Wikimedia Commons has media related to: Metasequoia

• Farjon, A. (2005). Monograph of Cupressaceae and Sciadopitys. Royal Botanic Gardens, Kew. ISBN 1-84246-068-4.
• Hanks, D.A. Crescent Ridge Dawn Redwoods Preserve (2005). http://www.dawnredwood.org
• Jahren, A. H. & Sternberg, L. S. L. (2003). Humidity estimate for the middle Eocene Arctic rain forest. Geology May 2003 pdf file
• Metasequoia Glyptostroboides (TSN 505864). Integrated Taxonomic Information System. Retrieved on September 25 2006.
• Metasequoia stumps, Axel Heiberg IslandPDF (804 KB)
• Williams C.J., LePage, B.A., Vann D.R., Tange, T., Ikeda, H., Ando, M., Kusakabe, T., Tsuzuki, T. and T. Sweda. (2003). Structure, allometry, and biomass of plantation Metasequoia glyptostroboides in Japan. Forest Ecology and Management, 180(103): 287-301. [1]
• Williams C.J., Johnson A.H., LePage, B.A., Vann D.R. and T. Sweda. 2003. Reconstruction of Tertiary Metasequoia Forests II. Structure, Biomass and Productivity of Eocene Floodplain Forests in the Canadian Arctic. Paleobiology, 29(2): 271-292. [2]

Further reading

External links

• Metasequoia in The Gymnosperm database
• The metasequoia organisation
• More information on the Dawn Redwood
• Giant redwoods in the U.K.