On a frosty April morning in 2021, a group of scientists from the U.S. set out with an ancient map, flashlights, a shovel, and a tape measure to search for a precious treasure buried 145 years ago.
Leading the small group was Professor Frank Telewski, a biologist and the leader of this society of researchers from Michigan State University. He was the guardian of the map that had been passed down through several generations.
Once they found the spot marked on the map and dug a hole with the shovel, scientist Marjorie Weber – the first woman to join the group – began to carefully excavate with her hands to prevent accidentally damaging the treasure.
She felt something hard beneath the earth, which excited everyone. However, it turned out to be a tree root. She continued a bit further until she hit something else – a stone. Something was amiss.
They checked the map again and realized they had miscalculated by about 60 centimeters. So, they resumed digging a little deeper.
And there it was: a half-liter glass bottle filled with sand and seeds. Weber says it felt like “bringing a healthy baby into the world.”
This treasure was buried in 1879 and after 15 decades, it was unearthed by this group of scientists working on one of the longest experiments in the history of biological sciences.
It was started by the botanist William J. Beal that year as a test to determine how long a seed can last and still be viable for germination.
The baton of its mission has passed among several guardians, many of whom have not seen – and perhaps will not see – its end. It is expected to conclude in 2100. Although even that could be extended.
“Being part of the Beal’s Buried Seeds Experiment has truly been a highlight of my career,” says Professor Lars Brudvig to BBC Mundo, one of the chosen scientists in the group.
“Unearthing and holding the bottle from 2021, last touched by Beal himself 141 years ago, and then witnessing one plant after another sprout from these seeds… wow. It has been a joy and an honor to be part of this team.”
The Bad Weed
William J. Beal was a botanical scientist at the College of Agriculture at Michigan State University, and he wanted to help local farmers increase their crop production by getting rid of weeds.
These weeds seemed to grow uncontrollably, and in that late 19th century era, farmers had to use a hoe and spend a lot of time trying to keep them at bay.
That’s why Beal wanted to understand their behavior, and he set out to investigate how long weed seeds could persist in the soil while remaining viable for germination.
To find an answer, he came up with the idea of filling 20 glass bottles with 50 seeds from 23 weed species. He buried them upside down – to prevent water from entering – in fields at Michigan State University. And to not forget their exact location, he made a map.
The original plan was to unearth a bottle every 5 years to check if the seeds were still viable.
He took charge of monitoring the experiment in the first decades, during which some of the seeds continued to sprout.
At 77 years old, he retired, so he handed the experiment over to his colleague Henry T. Darlington, a 31-year-old botany professor who had many years ahead of him.
The ‘Spartans’ of Beal
Upon seeing that the viability of the seeds remained in the early decades, by 1920 the period changed to 10 years. And as they kept germinating, by 1980 the wait was extended to 20 years.
As the decades passed, there have been seven custodians of the experiment. The “Spartans,” as they call themselves, seek to keep those bottles safe in a place away from the sight of the curious.
“It’s not signposted or guarded, but it’s quite secure, and no one would stumble upon it by chance. If you were to pass by, the location would seem like any other part of our campus of over 2,000 hectares,” Brudvig assures.
“We use a map to triangulate the location through key reference points.”
Since 2016, the leader of the experiment has been Frank Telewski, who appointed a guardian of a copy of the map in case something happened to him.
In 2021, they unearthed bottle number 14 of the 20 that Beal buried.
The Beautiful Sleepers
After nearly 150 years, some seeds are still sprouting, giving scientists more information about their latency or longevity.
Unlike decades ago, specialists have been able to conduct studies that Beal couldn’t have imagined, such as those involving DNA.
A recent molecular genetics test confirmed the presence of a hybrid plant of Verbascum blattaria and Verbascum thapsus, or common mullein, which was accidentally included among the seeds in bottle number 14.
Apparently, Verbascum plants have the longest latency, as others lost their germination ability within the first 60 years.
Although Beal’s initial goal was to help farmers eliminate weeds by determining seed longevity, after 144 years there’s still no definitive answer.
Brudvig likens the seeds they have to Princess Aurora from the story “Sleeping Beauty.”
“Latent seeds are alive, but ‘asleep’ and awaiting the right stimulus before awakening (germinating). However, while Princess Aurora waits for the kiss of her true love, seeds in the soil seed bank await stimuli like sunlight, proper temperature, or appropriate moisture conditions to sprout and begin growing,” she explains.
“One important thing to note is that seeds from different plant species can stay dormant for varying lengths of time,” Brudvig continues.
“At some point, it’s too late, even when they get the right stimulus. For the plant species studied in the Beal’s Seed Experiment, we’ve found that this time span ranges from <5 to >140 years.”
Weed… never dies?
The group is very careful with handling the seeds to achieve consistent results. They unearth the seeds at night to avoid any influence from sunlight. In the laboratories, they are capable of replicating natural environmental conditions.
“In fact, we use a growth chamber with carefully controlled temperature, light, and humidity when germinating plants for this experiment,” says Brudvig.
Beyond the questions originally posed by Beal, the experiment remains relevant for addressing additional questions that this botanist had not considered.
“The relevance of the experiment has also grown over time, in ways that I’m not sure Beal could have imagined almost 150 years ago,” says the scientist.
For instance, both rare native plant species and problematic invasive species can remain dormant in the soil, sometimes for many years, posing potential benefits and challenges for managing native ecosystems.
Learning more about this can aid efforts to restore native ecosystems, such as prairies and forests, from old farmland areas.
“Our findings help document which plant species, like Verbascum, could be problematic weeds for a restoration project like that, and which other species might not be, depending on how long a field was cultivated before being restored,” explains Brudvig.
It will take several more generations of Spartans to reach bottle number 20, which should be unearthed in the year 2100. However, scientists have not ruled out extending the period between each excavation.
Will they germinate more than 220 years later? Does the weed never die, as the saying goes?