Courtesy Cassidy Moody, Missouri Botanical Garden
In early May, a one-inch flower caused quite a stir at the Missouri Botanical Garden (MoBot). When Roy Gereau, MoBot’s assistant curator and Tanzania program director, received word of the blossom from colleague Andrew Wyatt, senior vice president of horticulture and living collections, he “immediately put the champagne on to chill.” Soon, the news traveled around the globe, making headlines in publications like National Geographic.
It’s the first time a flower has been observed on the critically endangered Karomia gigas tree—at least as far as plant scientists know. There are only 19 known trees in the wild, all of which are located on two patches of dwindling coastal forest in Tanzania in East Africa.
The first Karomia gigas tree and sapling were discovered in Kenya in 1977, and a decade later a taxonomist placed the species in the mint family. However, questions remained about the tree’s genus until the first delicate, purple-and-white flower was observed this year.
Courtesy Cassidy Moody, Missouri Botanical Garden
“Now we can write a complete description of the species,” says Gereau, noting that this is just one step toward preserving it for the future. “In terms of our breeding program, seeing the flower gives us a better idea of what’s likely to pollinate it, which gives us more ideas about the ecology and considerations for its conservation.”
MoBot’s participation in the project began in 2016, when Gereau and Wyatt joined Tanzanian and other international partners on a survey expedition to study several of the trees. In late 2017, MoBot came to an agreement with the Tanzanian government, and a few months later nearly 6,500 papery Karomia gigas fruits were shipped to St. Louis. After painstakingly extracting each seed by hand, MoBot staff were the first in the world to get the seeds to germinate in a controlled environment. The organization currently has 29 young trees—all about 8 feet tall—growing in its greenhouses.
“We’re very excited, not just because the flower had not been seen before … but also because it allows us to do controlled crosses within our greenhouses and actually produce potentially viable seed for future populations,” says Wyatt.
Later this year, experts in Tanzania will collect leaf samples from every known tree so that the genetic profile of each one can be catalogued. Plant scientists will use that information to crossbreed the trees to maximize the genetic diversity within the species.
Gereau says it’s not unlike the breeding programs zoos have for endangered animals. “You keep track of the parentage of every one of them and make sure you’re not breeding two close relatives,” he says. “People don’t think of that with plants … but the same considerations apply.”
Courtesy Cassidy Moody, Missouri Botanical Garden
Once the trees are established in MoBot’s living collection, those involved will work toward preserving it in the organization’s seed bank as well as eventually introducing genetically distinct individuals back into the wild.
Although Karomia gigas is not currently on public display, Wyatt hopes to introduce one into the Climatron later this year. “We could give you many examples of species that we’re working on in the same way: Naming them, we have them in cultivation, and we’re making sure that they don’t go extinct,” he says. “Karomia is a good ambassador for us to be able to show that process, but we’re doing it with hundreds of other species as well.”
