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水水杉杉((SShhuuii SShhaann)),, the Dawn Redwoood, (Metasequoia glyptostroboides), was first discovered in Central China in 1941 by forester, Professor T Kan, during a survey of Sichuan and Hubei Provinces. In the next two years, two more discoveries were made by Mr. Wang Zhan ( 王战). By extraordinary coincidence, at about the same time, and working quite independently, palaeobotanist Dr Shigeru Miki, identified a fossil leaf which he named Metasequoia (meaning ‘like a Sequoia ‘). However, it was a Chinese botanist, Professor Hu Xian Su (胡

Dawn Redwood in the Earth Sciences 先骕), who made the connection between Garden, Macquarie University the living trees and the fossils, and, together with Professor Zheng Wan Jun (郑万钧), finally named the tree ‘Metasequoia glyptostroboides1.

The Dawn Redwood is referred to as a ‘living fossil’ and we now know that at least three species of Metasequoia were widespread in the northern hemisphere from the late Cretaceous to the Miocene (from approximately 70 to 20 million years ago)1. There are a number of living (extant) relatives of this extraordinary descendant of those fossil trees, including the Swamp Cypress (Taxodium distichum) from the east coast of North America, the Californian Redwood (Sequoia sempervirens) and the Giant Sequoia (Sequoiadendron giganteum) from the west coast of North America. Remnants of a mummified forest of Metasequoia were discovered on the Canadian Arctic Axel Heiberg Island in the late 1980s, not fossilised, just dried and compressed, and, most amazingly, still capable of being burnt2!

The Dawn Redwood is unusual too, in that it is a deciduous conifer (yes, it does have cones, both female cones and tiny male cones in pendant spikes), and drops its leaves and small branchlets in autumn. It is considered an endangered species in its natural environment in China, as it is known only from a very few sites in Sichuan, Hubei and Hunan provinces where it grows in waterlogged areas of open forest. Individual trees are protected but not the surrounding habitats which are threatened by rapidly encroaching farms. Cones are much sought after by the horticultural industry so there is little or no natural recruitment of seedlings3. Male cones in pendant ‘catkins’ 1 Wikipedia: http://en.wikipedia.org/wiki/Metasequoia (spikes) 2 W.J.Beal Botannic Garden: http://www.cpa.msu.edu/beal/plantofweek/plants/metasequoia_glypto_20080804.pdf 3 IUCN Red list of endangered species: http://www.iucnredlist.org/details/32317/0 Female Cone: modified from Virginia Tech, Department of Forest Resources and Environmental Conservation, http://dendro.cnre.vt.edu/dendrology/syllabus/factsheet.cfm?ID=98 Map: modified from Encyclopedia of Life, http://eol.org/pages/1034875/maps

Alison Downing & Kevin Downing, Department of Biological Sciences, 13th May 2013

Female cone