The Dawn Redwood — A Living Fossil

Left: An herbarium specimen of Metasequoia collected from the Peabody’s tree.

Right: Fossil branch of a dawn redwood. Compare these oppositely arranged leaves to the herbarium specimen.

 

The dawn redwood (Metasequoia glyptostroboides) is a stately conifer (cone-bearing tree) with a long history that stretches back into the Age of Dinosaurs.

This close relative of the California redwood and the bald cypress, in essence a “living fossil,” was known only from the fossil record until it was rescued from the brink of extinction in the nick of geological time.

Above: Petrified stump of a dawn redwood from a 57-million-year-old forest at Stenkul Fiord, Ellesmere Island, Nunuvut, Canadian Arctic Archipelago.


Below: The former range of the dawn redwood (in pink).

 

Before its discovery in an isolated valley in central China the last living population of dawn redwoods consisted of no more than a few hundred trees. These survivors were the remnant of a species that once flourished over vast areas of the Northern Hemisphere and that dominated the vegetation of Arctic latitudes for some 35 million years, until the onset of hard frosts and glaciers drove it from the northern Polar regions.

Its rediscovery is a real detective story, an example of how scientific discovery is an international endeavor.

Above: Shigeru Miki’s 1941 paper in the Japanese Journal of Botany describing and illustrating for the first time the fossil Metasequoia.
 

 

Below left: Cleared and stained modern leaves of Metasequoia.

Below right: Petrified branch of a dawn redwood from Strathcona Fiord, Elsmere Island, Nunuvut, Canadian Arctic Archipelago.

 

In 1941, in the midst of the Second World War, Japanese paleobotanist Shigeru Miki first coined the name Metasequoia for a common but perplexing species well-known in Northern Hemisphere fossil collections under a variety of different names, all of which were incorrect. Then in July 1943 Chan Wang, a scientist with China’s National Bureau of Forest Research at Chongqi, discovered a tree growing in the town of Moudao in central China that seemed to be brand new to science.

It wasn’t until about five years later that the Chinese botanist H. H. Hu finally recognized that Wang’s living tree was the same kind as Miki’s fossil tree.

Above and left: Modern cones and seeds of the Metasequoia tree. Seeds are released when the cone scales dry out and reach maturity.

Right: Petrified branch of a dawn redwood from Strathcona Fiord, Elsmere Island, Nunuvut, Canadian Arctic Archipelago.

 

This discovery captured the imagination of scientists and the public alike, and it wasn’t long before the international distribution of dawn redwood seeds by Chinese and American scientists ensured that this priceless relic from the past would live to see another day.

The Metasequoia at the entrance to the Peabody Museum.

 

The Yale Peabody Museum has its own magnificent specimen of this survivor from the past just outside its front door. Although you probably know that conifers like pine, spruce and yew are evergreens, there are some, like the dawn redwood, that are deciduous. Indeed, in the fall the dawn redwood not only looses its leaves, but also the branchlets to which the leaves are attached.

This story of the dawn redwood emphasizes the importance of gathering as much information as possible about the plants and animals in today’s rapidly disappearing natural places. Without this, many pieces of the priceless heritage of evolution will be lost to future generations.