This July, a jury in Australia found a woman guilty of poisoning four of her estranged husband’s relatives. Three died. The nine-week trial gripped the world, in part because of how she went about it: slipping death cap mushrooms (Amanita phalloides) into their beef Wellington.
According to evidence presented at the trial, she foraged mushrooms from locations near her house after looking them up on the iNaturalist website. A search history on her phone revealed this and other damning details.
Like the woman, death cap mushrooms are infamous: They’re responsible for 90% of deaths by fungus — a fact we know thanks to the world’s herbaria.
What are herbaria? Picture an archive — only instead of a room stuffed with old papers, fill it instead with dried plants and fungi. This space is called an herbarium. The preservation of its contents allows them to be studied even when they’re not in season — or in some cases, no longer living on Earth at all.
In the case of the murderous mushroom scandal, herbaria would have helped document death cap’s existence in Australia, explains Barbara Thiers, the director emerita of the New York Botanical Garden Herbarium. This data would also allow a plant expert to verify the fungus in question.
“The reason we can tell one fungus, or plant, from another is because some scholar examined hundreds or thousands of herbarium specimens and characterized that plant and provided a means of telling it from every other species,” Thiers says.
She keeps track of herbaria. As of June 30, she says there were 403,871,563 specimens stored in 3,983 herbaria around the world.
Herbaria have a plethora of practical uses. They can be used to track phenology, the study of cyclic phenomena in nature, such as when a plant flowers or when a bird migrates, recurring natural events, and their relation to seasonal changes in the climate.
Because herbaria offer historic records of plants, they can also help scientists study how herbivory — feeding on plants — has changed over time, or gauge declines in pollination ecology.
And herbaria are indispensable when it comes to understanding how climate change may affect life on Earth. Just as a knowledge of human history helps us face the future, a knowledge of plant history can help us help future plants survive.
Yet just as many plant species are under threat or going extinct, so are herbaria — albeit for different reasons.
Why Study Dead Plants?
Botanist Luca Ghini established the first documented herbarium in Italy during the Renaissance. His collection has not survived the ravages of time, but universities and other bodies have established thousands of others around the world.
Herbaria often house flowering plants (angiosperms, which comprise up to 90% of plant species), but can also include mosses, ferns and other types of plants, along with fungi (more closely related to animals) and algae.
Collectively, the world’s herbaria store centuries of data. Yet science has only learned a fraction of what there is to know about the more than 300,000 identified species of flowering plants.
Few of us visit these herbaria, but we all rely on plant-based products and services, from pharmaceuticals to food. Even if we don’t understand how plants function and adapt, scientists need to — now more than ever. In the face of climate change, experts say, we need new conservation strategies and new crops as well.
Preserving reference specimens is essential to correct identification and, ultimately, the scientific method. It teaches us about the history of evolution — and in the Anthropocene, perhaps the future of evolution, too.
21st Century Herbaria
Herbaria may seem antiquated, rooms of dead plants with little relevance to our world today. Historically, they were used for taxonomy: naming and classifying plants. While that still matters — scientists keep discovering new plants — their uses today continue to expand.
“I think the trick with herbaria and natural history collections in general is that at the time of their collection, we really don’t fully understand their potential,” says Erin Sigel, collection manager of the Hodgdon Herbarium at the University of New Hampshire. “But the amazing thing is that the value only increases over time, because we don’t know how they’re going to be used in the future. It’s kind of magical.”
Two modern uses are digitization and genetic sequencing.
To digitize a plant, herbaria try to do two things. First, they take a high-resolution photo of a specimen with a label explaining where the plant was collected, by whom, with ecological information. Second, they add the photo and accompanying information to large databases called thematic collection networks that have portals and link a bunch of data together. These efforts aim to make valuable “dark data” — information stored in physical collections — readily available to researchers, educators, and the public.
“By pooling all our data together, we have much larger data sets for anyone interested in accessing that data,” Sigel explains. “One of the most immediate uses of all this digitized data is that it’s available to researchers around the world. It’s much more accessible online.”
Digitization also helps preserve specimens — some of which are hundreds of years old — from constant handling or the potential risks from shipping them to faraway labs that want to study them. “It’s really important to retain the actual specimen,” Sigel says. “But if someone can use it digitally, it’s less wear and tear.” Meanwhile, the specimen remains available if a researcher wants to examine its genetic material, such as its DNA.
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The data for each specimen is important, but additional value comes from collecting disparate details from multiple specimens or herbaria. “By pooling data into datasets, we can see how a plant’s distribution has changed over time,” Sigel says. “Have lower elevation plants moved to higher elevations because of higher temperatures? Are plants on mountaintops going extinct because there’s nowhere for them to go?”
Another expanding use is genetic sequencing. Over the past decade or so, researchers have been able to sequence whole genomes from herbaria.
Scientists evaluate patterns of genetic variation in plants to see how they’re related to each other and how they’ve evolved.
“It helps us understand how the Earth and its populations have changed over time,” Sigel says.
Thiers offers an example of how this has helped to understand a species that has become a problem in the United States.
“Cheat grass is an incredible invasive throughout the West, costing millions, maybe billions, because it’s replacing all the good [plants] we feed to cattle.” It’s not invasive in Europe, she points out, so why has it gone haywire here? Analysis of herbaria specimens going back decades “showed that once specimens came here, they came in contact with each other, began to hybridize and take over the West. You can sequence genes and get an understanding of how that species existed at a point in time, to reconstruct that. Herbaria provide a historical context you can’t get any other way.”
Why Herbaria Are Under Threat
The number of herbaria worldwide is growing, Thiers says — at least on paper.
“But they are being killed by the removal of resources,” she continues. “A few in Europe have over a million specimens with one person working with that collection. Many herbaria have no budget at all. Zero budget. That is really more the problem.”
For example, the University of Arizona’s herbarium has no budget, despite its collection of nearly 450,000 plant specimens. The University of Maryland’s has been taken offline. Now a group of volunteers go in there on the weekends to do what they can: prepare specimens that were not completed when the herbarium closed, check for insect infestations, and try to answer information requests that come in.
“These are the day-to-day tasks of managing an herbarium. The most important one is monitoring for insect infestation, which is a constant threat to all herbaria,” Thiers says.
When it comes to budgets, plant collections are easy targets. Traditionally housed on campuses across the country, many schools no longer want to dedicate the money or the space to maintain them.
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When it comes to actual closure, Thiers says that tiny herbaria seem to be most threatened. Up until now, though, other collections have adopted those orphaned plants.
“To a certain extent, one herbaria has always absorbed another,” Thiers says.
For example, Iowa State University’s herbarium has grown in recent decades, in part because it took in the collections of smaller herbaria.
But now some big collections are threatening to disappear. Duke University created shockwaves in February 2024 when it announced it was closing its massive herbarium. Thiers says the administration “just assumed someone could step in and absorb it. I’ve seen more than a dozen absorbed, but these were 20,000 [specimen] collections, not 825,000. We were confronted for the first time [with the fact] that no other herbarium may be in a position to take on this very large and important collection.”
Duke’s decision sparked backlash from scientists and caused real fear, too. For now, its herbarium is still functioning, and Thiers says the administration has stopped talking about it. That doesn’t mean they plan to keep it, though.
“They thought they could just give it away, no more expenditure, and someone could come and take it,” Thiers says. But that process of transferring a collection is expensive, and someone needs to pay for it.
“Basically, [transfers are] never done for less than a dollar a specimen,” Thiers explains. “It’s essentially a million dollars just to move the herbarium, and that assumes there’s somewhere to put it — the quantity in shortest supply.”
And while Duke is the first major collection that may close, smaller collections continue to shut their doors and budgets continue to shrink. “What we’re really concerned about is the slow attrition and the prospect that very large herbaria could fail,” Thiers says. “We have no idea what could happen in that case.”
The Fate of Federal Funding
In the United States one critical source of funding — for transfers, preservation, expansion, and making plant collections accessible — comes from federal agencies, particularly the National Science Foundation. It’s the main federal government funder of herbaria, Thiers says, with occasional help from other federal groups.
Until now, for example, the NSF has funded numerous plans and projects to digitize plant collections. In the southeastern United States, Sigel says, NSF funding allowed collections to be digitized across more than 100 herbaria. As a result, researchers worldwide can access more than 3 million specimens. Other federal funds support cataloging specimens and improving their storage, conservation of threatened and endangered plant species (which often involve herbarium collections), and training the next generation of botanists.
But times have changed, and much of this federal funding has become uncertain or threatened. Under the Trump administration, DOGE has cut hundreds of millions of dollars to federal agencies that fund herbaria.
President Trump’s grudge against Harvard hasn’t helped.
Sigel’s school in New Hampshire was part of an effort to digitize a collection from Asia. At least 40 herbaria were involved, but the project was led by Harvard, and “that project is coming to a rather abrupt end,” Sigel says.
She also knows several people who’ve had their research grants revoked that focused on taxonomic diversity and genomic sequencing of plants. As a result, studies in biodiversity — including evolution, extinction, climate change, and other crucial scientific questions — are suffering.
As of July 9, the NSF has canceled more than 1,500 research grants, including some related to herbaria. Nearly 90% of eliminated grants were related to “diversity, equity, and inclusion.” Some nonprofits who have lost funding speculate that the Trump administration includes projects related to biodiversity when making DEI cuts. When it comes to herbaria, Thiers says “many of the NSF grants that were cancelled had to do with training groups of people who are underrepresented in science and training for students in general. All the things that we have done to try to make collections more relevant have been targeted for cuts,” Thiers says, adding, “It’s already been bad, and can only get worse.”
Invisible Extinctions?
Most people in the public will never notice if an herbarium closes its doors.
In many ways, that echoes the disappearance of plant species around the world, with many populations shrinking or disappearing without a ripple.
Without the scientific expertise of herbaria, we may never know that those plants have gone extinct — or maybe that they existed at all.
“Documenting extinction really helps us understand how our actions as a human species have impacted the world,” Sigel says.
Aside from admitting our guilt, why does documenting extinction matter?
“To some people it doesn’t matter,” Sigel says. “But I think the world around us is shaped by biodiversity. We don’t exist in the world as species unto ourselves. And most of the things that shape our reality really come from other organisms, like the food we eat and the medication we use. Without that knowledge of what biodiversity exists in the world, I think we’re lost.”
Previously in The Revelator:
All the Plants We Cannot See
