How Much Wood Could a Museum Collect? Much More Than a Woodchuck Could | Smithsonian Voices

From providing forensic wooden “fingerprints” to insights on structural engineering, the museum’s collection of rare and wonderful lumber is a prized scientific resource

The vast majority of the more than 148 million specimens and objects in the National Museum of Natural History’s collections are off display. But everything — whether it be a moth, meteorite, moss or mammoth — tells a story that helps museum researchers make sense of the natural world. The Specimen Spotlight series highlights different specimens or objects from the world’s largest natural history collection that shed light on why we collect.

The National Museum of Natural History is renowned for its iconic objects like the Hope Diamond and the Nation’s T. rex. 

With so many spectacular specimens, it could be easy to miss the museum’s wood collection. Which wood be a big mistake as these scientific samples form one of the world’s most important assemblages of lumber. “At the Museum Support Center, our collections storage facility in Maryland, we have about 43,000 wood specimens spanning over 3,000 genera — that makes us the second largest wood collection, or xylarium, in the United States and fifth largest in the world,” said research botanist Kenneth Wurdack, the curator of the museum’s wood collections.

It is very hard to differentiate tree species based solely on their wood. Thankfully, some 60% of the museum’s wood collection is vouchered, meaning the specimens are verified down to their taxonomic genus and species. This is done by using a herbarium, or dried, specimen with intact leaves and flowers to document the wood source. Scientists from around the world visit the collection to compare samples and distinguish between wood types, which helps them combat illegal lumber trafficking, craft conservation plans and even shed light on extinct tree species.

“It’s surprising what plants can get woody,” said Wurdack. “Looking through the collection, going across the bursting drawers of wood blocks or even just pieces of stems, you see all this diversity. And there’s even more under the surface microscopically!” 

In honor of the recently celebrated National Tree Day, let’s open some drawers and reveal why the museum’s wood collection is an indispensable resource for science.

Tracking Rosewood

Illegal wood trafficking is the most profitable natural resource crime on our planet. And lumber smugglers are aided by a lack of forensic timber identification tools. This allows unscrupulous importers to evade endangered species laws.

For example, rosewood — a highly coveted type of wood native to Madagascar — is prized for its rich finish and is often used to craft fine instruments like guitars and violins. But its high market value has fueled extensive illegal trafficking, pushing the species to the brink of extinction. 

To remedy situations like this, a team from the National Fish & Wildlife Forensics Laboratory recently spent time in the museum’s wood collection. Their goal: to build reference libraries of chemical “fingerprints” from different woods to help government officials regulate trade and catch illegal traffickers.  

“Using small slivers of various rosewoods, they created chemical profiles,” explained Wurdack. “At their forensic lab in Oregon, they have a special rapid analytical method that allows them to fingerprint the wood based on its chemistry. Once the wood is verified down to the species, they then determine if it’s a sneaky look-a-like or regulated under the Convention on International Trade in Endangered Species treaty.”

But why don’t researchers use DNA, which can distinguish among species, to identify smuggled wood? Most wood cells die once a tree reaches maturity. They become degraded into small fragments that require hours of lab work and significant expense to verify. Chemical fingerprinting allows customs agents and law enforcement to more efficiently identify rosewood species and regulate the international trade of these imperiled woods.

“Weird Woods” 

Lianas are climbers. Abundant in the tropics, their woody stems battle with trees to be the dominant plants at the top of the forest canopy, desperately trying to capture the most sunlight.

While lianas look and act like vines, they are actually something stranger. According to Pedro Acevedo, a recently retired curator of botany at the museum, tropical lianas are considered a “weird wood” due to their odd structure. Woody plant stems usually have three distinct layers — xylem (or the innermost structural support that often has seasonal growth rings), phloem (or the middle layer of living tissue responsible for food transfer) and finally the bark covering the outer perimeter. Instead of forming a single ring of growth like most trees, the three sections are scrambled and can vary between specimens of the same species.

These combinations allow lianas to climb to significant heights — including over 100 feet in the Amazon rainforest — without breaking, while still transporting water and nutrients through their stems. They provide solid structural support in an amazing feat of natural engineering. 

Acevedo sought to understand how these strange structures came to be. By sampling the hundreds of tropical lianas from around the world in the museum’s wood collection, Acevedo and his colleagues looked at their anatomy and evolutionary relationships to see how “weird wood” evolved over time.  

“The hope is to see what properties make wood stronger to use in material sciences like engineering,” said Wurdack. “Their unique makeup could be a clue to building taller wood structures that are more weather resistant and friendlier to the environment than something like concrete.”

Tree-mendous Species 

The museum’s collections are a vital source for preservation of rare and extinct species, and woods are no exception. Unfortunately, threats like deforestation linked to agriculture and urbanization, as well as introduced diseases, have decimated the populations of several species of trees. Some now only exist as specimens in the museum’s collection.

Welwitschia mirabilis, also known as tree tumbo, is a desert gymnosperm plant native to Namibia in Africa. This tree is considered a living fossil — the last survivor of a lineage of plants that evolved over 100 million years ago. Attached to the crown of its mostly underground woody stem, it has two long, strap-like leaves that continue to grow over the plant’s entire life and can reach up to 13 feet (4 m) in length. “Tumbos” can grow for centuries or more, with some individuals reaching thousands of years old. Scientists treasure these long-lived plants because they reveal a unique look about how species adapt to environmental changes over hundreds of years. The museum’s wood collection has one of the few large specimens to exist in any xylarium; while barely a foot in diameter, this specimen is likely hundreds of years old.

Another unusual find in the wood collection is a specimen of Torreya taxifolia — the Florida torreya. This tree is one of the rarest conifers in the world, endemic to a narrow range of bluffs and ravines along the Apalachicola River in northern Florida. The spread of a deadly disease in the mid-twentieth century wiped out almost all of the species’ reproductive age trees. Now reduced to just 0.22% of its former range, the species continues to decline as most stump sprouts fail to survive the disease.

The Florida torreya’s rot-resistant wood was locally used for fence posts, shingles and even Christmas trees back in the day, but now is critically endangered. The tree exists in cultivation at centers like the Atlanta Botanical Garden, which is working to conserve and protect the species’ genetic material. However, since their drastic decline, wood samples like this one can only be found in a few museum collections.  

According to Wurdack, the preservation of rare and endangered species, like the Florida torreya, remains a top priority for collecting and studying woods. “Amid the anthropogenic and climatic pressures tree species are facing today, it’s our job as scientists to document what’s out there before its gone,” he said. “In the United States, we only use a handful of the woody species out there. The museum’s wood collection stands as a testament to what can be achieved by uniting the remarkable diversity of the world’s wood species.”

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