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Health, Science, Environment

MoBot scientists grow endangered Tanzanian trees in greenhouse to save it in wild

Seedlings of a rare Tanzanian tree, the Karomia gigas, in a greenhouse at the Missouri Botanical Garden.
Andrew Wyatt | Missouri Botanical Garden
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Missouri Botanical Garden scientists are cultivating an endangered Tanzanian tree, Karomia gigas, to prevent it from becoming extinct.

No one has seen the flower of the 60-foot-tall Karomia gigas tree in Tanzania; scientists at the Missouri Botanical Garden hope they’ll be the first.

For decades, botanists at the garden have been helping the Tanzanian government prevent rare and threatened trees from becoming extinct. Scientists recently started growing one of those trees, the Karomia gigas, in a greenhouse at the garden. There are 19 members of the species in the wild.

The garden’s scientists are cultivating the trees in St. Louis because conservationists have had no luck growing them in Tanzania. The seeds are extremely vulnerable to fungus and insect predators, said Roy Gereau, the garden’s Tanzania program director.

“The seeds are actually attacked while they’re still on the tree,” Gereau said. “By the time they hit the ground, they don’t have a chance.”

As a result, very few of its seeds are viable. The garden’s scientists received 6,500 seed capsules from the Tanzania Tree Seed Agency, but the researchers were only able to germinate 30.

Scientists know very little about Karomia gigas, a member of the mint family. Botanists thought the species — originally found in Kenya — was extinct until it was discovered in southern Tanzania in 1993.

“We’re not even absolutely sure that this species has been placed in the right genus,” Gereau said.

Gereau is working with Andrew Wyatt, the garden’s senior vice president of horticulture and living collections. If the seedlings in their greenhouse continue to thrive, they want to find out if it can be propagated. They also hope to replicate their methods with other rare Tanzanian trees.

Missouri Botanical Garden scientists last saw wild specimens on a 2016 expedition in Tanzania.

“I’ve only seen it when it’s dormant. It’s a beautiful species when you see it in the wild,” Wyatt said. “I’m interested in plants, in general; the fact that we can actually work to save a species from extinction like this.”

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