HISTORICAL FOLIAGE & THE FOSSIL RECORD

The colder seasons of autumn and winter are a wonderful time to explore Vancouver. The riot of yellow, orange and green from the cities autumn palette slowly fades to deep gold and soft browns. 

Fallen debris you crunch through send up wafts of earthy smells that whisper of decomposition, the journey from leaf to soil.

It is a wonderful time to be out and about. I do love the mountain trails but must confess to loving our cultivated gardens for their colour and variety. 

We have some lovely native plants and trees and more than a few exotics at Vancouver's arboreal trifecta — Van Dusen, Queen E Park and UBC Botanical Gardens. One of those exotics, at least exotic to me, is the lovely conifer you see here is Metasequoia glyptostroboides — the dawn redwood. 

Of this long lineage, this is the sole surviving species in the genus Metasequoia and one of three species of conifers known as redwoods. Metasequoia are the smaller cousins of the mighty Giant Sequoia, the most massive trees on Earth. 

As a group, the redwoods are impressive trees and very long-lived. The President, an ancient Giant Sequoia, Sequoiadendron giganteum, and granddaddy to them all has lived for more than 3,200 years. While this tree is named The President, a worthy name, it doesn't really cover the magnitude of this giant by half.   

This tree was a wee seedling making its way in the soils of the Sierra Nevada mountains of California before we invented writing. It had reached full height before any of the Seven Wonders of the Ancient World, those remarkable constructions of classical antiquity, were even an inkling of our budding human achievements. And it has outlasted them all save the Great Pyramid of Giza, the oldest and last of those seven still standing, though the tree has faired better. Giza still stands but the majority of the limestone façade is long gone.

Aside from their good looks (which can really only get you so far), they are resistant to fire and insects through a combined effort of bark over a foot thick, a high tannin content and minimal resin, a genius of evolutionary design. 

While individual Metasequoia live a long time, as a genus they have lived far longer. 

Like Phoenix from the Ashes, the Cretaceous (K-Pg) extinction event that wiped out the dinosaurs, ammonites and more than seventy-five percent of all species on the planet was their curtain call. The void left by that devastation saw the birth of this genus — and they have not changed all that much in the 65 million years since. Modern Metasequoia glyptostroboides looks pretty much identical to their late Cretaceous brethren.

Dawn Redwood Cones with scales paired in opposite rows

They are remarkably similar to and sometimes mistaken for Sequoia at first glance but are easily distinguishable if you look at their size (an obvious visual in a mature tree) or to their needles and cones in younger specimens. 

Metasequoia has paired needles that attach opposite to each other on the compound stem. Sequoia needles are offset and attached alternately. Think of the pattern as jumping versus walking with your two feet moving forward parallel to one another. 

Metasequoia needles are paired as if you were jumping forward, one print beside the other, while Sequoia needles have the one-in-front-of-the-other pattern of walking.

The seed-bearing cones of Metasequoia have a stalk at their base and the scales are arranged in paired opposite rows which you can see quite well in the visual above. Coast redwood cone scales are arranged in a spiral and lack a stalk at their base.

Although the least tall of the redwoods, it grows to an impressive sixty meters (200 feet) in height. It is sometimes called Shui-sa, or water fir by those who live in the secluded mountainous region of China where it was rediscovered.

Fossil Metasequoia, McAbee Fossil Beds

Metasequoia fossils are known from many areas in the Northern Hemisphere and were one of my first fossil finds as a teenager. 

And folk love naming them. More than twenty fossil species have been named over time —  some even identified as the genus Sequoia in error — but for all their collective efforts to beef up this genus there are just three species: Metasequoia foxii, Metasequoia milleri, and Metasequoia occidentalis.

During the Paleocene and Eocene, extensive forests of Metasequoia thrived as far north as Strathcona Fiord on Ellesmere Island and sites on Axel Heiberg Island in Canada's far north around 80° N latitude.

We find lovely examples of Metasequoia occidentalis in the Eocene outcrops at McAbee near Cache Creek, British Columbia, Canada. I shared a photo here of one of those specimens. Once this piece dries out a bit, I will take a dental pick to it to reveal some of the teaser fossils peeking out.

The McAbee Fossil Beds are known for their incredible abundance, diversity and quality of fossils including lovely plant, insect and fish species that lived in an old lake bed setting. While the Metasequoia and other fossils found here are 52-53 million years old, the genus is much older. It is quite remarkable that both their fossil and extant lineage were discovered in just a few years of one another. 

Metasequoia was first described as a new genus from a fossil specimen found in 1939 and published by Japanese paleobotanist Shigeru Miki in 1941. Remarkably, the living version of this new genus was discovered later that same year. 

Professor Zhan Wang, an official from the Bureau of Forest Research was recovering from malaria at an old school chum's home in central China. His friend told him of a stand of trees discovered in the winter of 1941 by Chinese botanist Toh Gan (干铎). The trees were not far away from where they were staying and Gan's winter visit meant he did not collect any specimen as the trees had lost their leaves. 

The locals called the trees Shui-sa, or water fir. As trees go, they were reportedly quite impressive with some growing as much as sixty feet tall. Wang was excited by the possibility of finding a new species and asked his friend to describe the trees and their needles in detail. Emboldened by the tale, Wang set off through the remote mountains to search for his mysterious trees and found them deep in the heart of  Modaoxi (磨刀溪; now renamed Moudao (谋道), in Lichuan County, in the central China province of Hubei. He found the trees and was able to collect living specimens but initially thought they were from Glyptostrobus pensilis (水松). 

A few years later, Wang showed the trees to botanist Wan-Chun Cheng and learned that these were not the leaves of s Glyptostrobus pensilis (水松 ) but belonged to a new species. 

While the find was exciting, it was overshadowed by China's ongoing conflict with the Japanese that was continuing to escalate. With war at hand, Wang's research funding and science focus needed to be set aside for another two years as he fled the bombing of Beijing. 

When you live in a world without war on home soil it is easy to forget the realities for those who grew up in it. 

Zhan Wang and his family lived to witness the 1931 invasion of Manchuria, then the 1937 clash between Chinese and Japanese troops at the Marco Polo Bridge, just outside Beijing. 

That clash sparked an all-out war that would grow in ferocity to become World War II. 

Within a year, the Chinese military situation was dire. Most of eastern China lay in Japanese hands: Shanghai, Nanjing, Beijing, Wuhan. As the Japanese advanced, they left a devastated population in their path where atrocity after atrocity was the norm. Many outside observers assumed that China could not hold out, and the most likely scenario was a Japanese victory over China.

Yet the Chinese hung on, and after the horrors of Pearl Harbor, the war became genuinely global. The western Allies and China were now united in their war against Japan, a conflict that would finally end on September 2, 1945, after Allied naval forces blockaded Japan and subjected the island nation to intensive bombing, including the utter devastation that was the Enola Gay's atomic payload over Hiroshima. 

With World War II behind them, the Chinese researchers were able to re-focus their energies on the sciences. Sadly, Wang was not able to join them. Instead, two of his colleagues, Wan Chun Cheng and Hu Hsen Hsu, the director of Fan Memorial Institute of Biology would continue the work. Wan-Chun Cheng sent specimens to Hu Hsen Hsu and upon examination realised they were the living version of the trees Miki had published upon in 1941. 

Hu and Cheng published a paper describing a new living species of Metasequoia in May 1948 in the Bulletin of Fan Memorial Institute of Biology.

That same year, Arnold Arboretum of Harvard University sent an expedition to collect seeds and, soon after, seedling trees were distributed to various universities and arboreta worldwide. 

Today, Metasequoia grow around the globe. When I see them, I think of Wang and all he went through. He survived the conflict and went on to teach other bright, young minds about the bountiful flora in China. I think of Wan Chun Cheng collaborating with Hu Hsen Hsu in a time of war and of Hu keeping up to date on scientific research, even published works from colleagues from countries with whom his country was at war. Deep in my belly, I ache for the huge cost to science, research and all the species impacted on the planet from our human conflicts. Each year in April, I plant more Metasequoia to celebrate Earth Day and all that means for every living thing on this big blue orb.  

References: 

• https://web.stanford.edu/group/humbioresearch/cgi-bin/wordpress/?p=297
• https://humboldtredwoods.org/redwoods