The alien-like blooms and putrid stench of Amorphophallus titanum, better known as the corpse flower, draw big crowds and media coverage to botanical gardens each year. In 2015, for instance, more than 75,000 people visited the Chicago Botanic Garden to see one of its corpse flowers bloom. More than 300,000 people viewed it online.
But despite the corpse flower’s fame, its future is uncertain. As of 2019, roughly 500 specimens were living in botanical gardens and some university and private collections—but records show that they’re closely related. This lack of genetic diversity could make them more vulnerable to a host of problems, such as disease or a changing climate.
The corpse flower isn’t doing much better in its native home of Sumatra, where its numbers are dwindling because of deforestation for lumber and crops. In 2018, the International Union for Conservation of Nature (IUCN) listed the plant as endangered. There are fewer than 1,000 individuals still in the wild.
To combat the lack of genetic diversity in the corpse flower and six other species with shallow gene pools, the Chicago Botanic Garden has spearheaded Tools and Resources for Endangered and Exceptional Plant Species, or TREES. The program is promoting widespread genetic testing across partnering botanic gardens, as The New York Times reported in December. This lets participants create a database of the plants’ family trees, so to speak, to make more informed breeding choices and increase genetic diversity.
TREES could pave the way for future plant reintroductions into the wild, should any of the seven species continue to dwindle or come too close to extinction, says Jeremie Fant, a conservation scientist with the Chicago Botanic Garden. However, some experts have expressed concern about bringing genetics from foreign-grown plants into their native habitats.
The corpse flower is a tricky plant to preserve outside of its native habitat. It rarely blooms, and it needs specific heat and humidity conditions to mimic its home in the wild. Like many of the plants in the TREES program, the finicky flower also produces recalcitrant seeds, which can’t be easily stored because drying and freezing—the main way seeds are preserved—will kill them. (Other plants in the program simply produce too few seeds to make seed banking a viable option.)
While the Chicago Botanic Garden is taking charge of the corpse flower, the National Tropical Botanic Garden in Hawaii is heading the collecting and testing of two species: Hibiscus waimeae and the critically endangered Phyllostegia electra. Two additional botanic gardens are focusing on other species to tackle this widespread issue.
“We at botanic gardens have to work together to save some species,” Fant says. “Because we can’t do it on our own.”
Currently, most plant conservation happens in seed banks, such as the International Potato Center in Peru and the International Institute of Tropical Agriculture in Nigeria. These banks of genetic information regularly freeze seeds for long-term research and use. In Arctic Norway, the Svalbard Global Seed Vault holds a backup collection of seeds from around the world in case local stores are compromised. But this method doesn’t work for plants with recalcitrant seeds.
Usually, it is warm-climate plants—including the corpse flower—that produce these seeds, but there are exceptions, including oak. According to research out of Royal Botanic Gardens, Kew, in the United Kingdom, 36 percent of “critically endangered plants” have recalcitrant seeds. Many well-known crops also produce recalcitrant seeds, such as coconuts.
If a plant is socioeconomically important—like coconuts—and produces recalcitrant seeds, conservationists will often create what are called “field gene banks,” according to Nigel Maxted, a professor of plant genetic conservation at the University of Birmingham in the U.K., who isn’t part of the TREES program. These field gene banks feature many of the same plants growing in the same area. They can take up a lot of space, and the proximity of the plants to each other opens them up to other threats as well. “Disease could very easily go through the whole lot,” Maxted says.
Given this, preserving species by spreading individual plants across many botanic gardens, or other collections, can be a useful bulwark against extinction, because it greatly decreases the likelihood that every single plant will die at once, says Susan Pell, deputy executive director of the United States Botanic Garden, a TREES participant.
But fostering genetic diversity within botanic gardens can be difficult, especially with finicky and rare species. Like many plants, corpse flowers can reproduce in different ways. Sometimes, they reproduce asexually: A tuber-like bulge at the base of their stem, called a corm, grows large and eventually splits, producing multiple genetically identical plants. While this has effectively increased the raw number of corpse flowers in botanic gardens, it’s done little for the population’s genetic diversity.
Corpse flowers can also reproduce sexually, which requires pollination by insects—or, in botanic gardens, by humans wielding paint brushes. There’s no set schedule for a corpse flower to bloom; each plant takes a variable number of years and blooms unpredictably based on conditions such as heat, light, humidity, and other factors.
To help breed on this unpredictable schedule, the Chicago Botanic Garden is creating a store of corpse-flower pollen, which can be sent across the country when another specimen that isn’t closely related blooms. These targeted cross-pollination efforts could lead to more genetically robust offspring. While TREES has yet to lead to a crossing of corpse flowers, the Chicago Botanic Garden has used the methodology to strategically cross another plant: Brighamia insignis, also known as a cabbage-on-a-stick plant, which is critically endangered.
The TREES program is starting from a place of low genetic diversity for the corpse flower and its peers. Over the last 100 years, there have only been 20 documented collections of the plants from the wild for botanic gardens.
Sometimes, botanic gardens will get rare plant genetics from nurseries and private collections. For example, some of the U.S. Botanic Garden’s corpse flowers were acquired as seeds from a plant grower in Hawaii. But, as collecting plants from the wild can be difficult and expensive, the botanic gardens will usually propagate the specimens and share the offspring with other collections. In the case of plants with low genetic diversity, this means an increase in raw numbers—but does little for genetic health.
“In terms of genetic diversity, it’s hopeless,” Maxted says.
TREES may help, he adds. The program’s approach has been successfully deployed in the animal kingdom for a long time. For example, many zoos and conservation efforts create studbooks, or documents used to track the family trees of specific species. This tactic has been used to follow the lineages of myriad threatened species around the world, including the red panda.
“In general,” Maxted says, “all you’re looking for is to maximize variation.”
While TREES could increase genetic diversity for domestic corpse flowers, some researchers aren’t sure the flower—and plants more generally—should necessarily be reintroduced into the wild. This is particularly true for plants in botanic gardens that are located far away from their native range.
There are two competing trains of thought, Pell says. The first is that only plants that were grown nearby should be reintroduced into a wild ecosystem. For the corpse flower, this could mean pulling from the Bogor Botanical Garden in Indonesia, which has a few specimens. The rival concept supports the idea of putting foreign-grown plants back into nature and letting natural selection play out, even if it means that the foreign plants may thrive or outcompete their wild counterparts. (While TREES aims to make it possible to reintroduce the corpse flower into the wild if conservationists decide it’s necessary, so far there haven't been any efforts to do so.)
Reintroduction can also take a lot of time, money, and effort, says Joyce Maschinski, director of plant conservation at San Diego Zoo Global and president and CEO of the Center for Plant Conservation. So can the long-term monitoring and care that the plants would need to thrive in the wild. Similarly, moving plants across borders can be difficult, and the laws surrounding that vary from country to country—although, she adds, moving pollen or seeds from botanic garden plants is likely easier.
Despite the challenges, conservation organizations and botanic gardens have become skilled at reintroducing plants, Maschinski says. Beyond keeping detailed records, these groups monitor and care for the plants after they’re placed in the wild, including fencing off newly planted areas and watering them.
For some plants, this approach may be the only hope. While there are concerns about reintroducing foreign-grown plants back into the wild, Maschinski adds, particularly rare species may otherwise go extinct.
If a time comes when reintroduction becomes a necessity, programs like TREES could ensure a healthy and diverse population of corpse flowers and other currently endangered plants, Fant says. The researchers involved in TREES also say they hope the methods could be rolled out to other species that could benefit, as the need arises. The program is already growing and asking for samples from botanic gardens—including locations outside of the U.S., such as Indonesia’s Bogor Botanic Garden.
According to Maschinski, plants are vital parts of their natural habitats—so preserving some plant species can have a “cascade effect” on the environment. For instance, they feed bugs, which feed birds, which feed other animals. But according to Pell, the corpse flower’s role in its native habitat is relatively unknown. Whether or not it’s a keystone species, the corpse flower could still be a valuable ambassador—one that raises awareness of the plight faced by many other species, she says.
“I sort of think of the corpse flower as the panda of the plant world, in a lot of ways,” she says. “It is just so fascinating and people are so taken in by it that it can be the kind of spokesperson for the importance of conserving all of our biodiversity—and certainly in the plant world.”
Even if the TREES program doesn’t lead to some corpse flowers being reintroduced in the wild, there’s value in protecting the species in botanic gardens, says Cyrille Claudel, a biologist at the University of Hamburg in Germany. It also might be easier to simply leave the plants alone in the wild, he says, rather than attempting to bring them back in full. Safeguarding captive corpse flowers would allow the curious to continue their research on the plants—or let people simply marvel at them.
The plant is worth saving just for its own sake, Claudel adds: “It’s probably just the coolest species on Earth, so I would very much like it to be preserved in nature, and cultivation.”