Science & Nature

Rare flowering plant creates Botanical Garden buzz

The American columbo produced its first bloom 19 years after being planted at the North Carolina Botanical Garden.

American columbo plant against green background.
The American Columbo is blooming at the North Carolina Botanical Garden, 19 years after the seed was planted. (Johnny Andrews/UNC-Chapel Hill)

Nature’s cycles are sometimes easy to predict. We knew the cicadas would emerge long before they started buzzing this summer. April’s solar eclipse was a spectacular sight – but not a surprise.

Other times, nature can be much more mysterious.

About a month ago, habitat gardens curator Chris Liloia was weeding in the mountain habitat at the North Carolina Botanical Garden when she made an exhilarating discovery. One of the garden’s American columbo plants was starting to bloom – 19 years after Liloia planted it.

“My dramatic response to the first signs of a flowering stalk must’ve been confusing to my volunteers until I told them the story,” Liloia said, smiling at the memory. “I sent an email out to the whole staff about it, and that’s when all of the excitement just sort of kicked in.”

Since then, the columbo has grown to roughly 5 feet tall. As a monocarpic plant, the columbo blooms only once in its lifetime, often 20 to 30 years after it is planted. Then, much like the cicada, it dies – disappearing almost as abruptly as it arrived.

The mercurial plant has drawn crowds at the garden throughout the spring, and visitors might only be able to see it for a few more weeks before it dies and leaves behind its seeds.

Just how unusual is the columbo’s reproductive method?

“Given the full array of plants, it’s not a one-off, but I would say that it’s a comparatively small percentage of them that reproduce with this strategy,” said Pat Gensel, a paleobotanist and professor in the College of Arts and Science’s biology department. “It’s pretty exciting when one of these truly monocarpic plants flower.”

As a paleobotanist, Gensel studies the evolution of plants over billions of years. Through studying fossils, she knows of monocarpic plants that grew in swamps 320 million years ago and followed a similar reproductive pattern to the columbo. She pointed to two evolutionary theories as to why a plant would only bloom once then die.

One theory is that monocarpic reproduction is an adaptation that allows plants to survive harsher environments – such as a swamp – by gradually building up their energy over long periods of time before flowering. Another idea is that monocarpic plants employ the strategy to minimize the risk of predation on its seeds and reproductive parts by animals.

The columbo is typically found in dry, rocky environments, such as in the North Carolina mountains. It doesn’t grow in the North Carolina piedmont, unless planted. The blooming columbo at the garden is one of seven that were planted in 2005, with the seeds coming from garden founder Ritchie Bell’s private garden.

The other six columbo plants have yet to bloom, and there’s no way to predict precisely when those other plants could flower – perhaps next year, perhaps in 10 years.

“There’s ideas, and some knowledge, but I think it’s something that people are still studying,” Gensel said. “When I teach botany, I tell students that plants have to grow up before they can flower. They have to reach a certain kind of size, or often they have to produce a certain number of leaves, or they have to produce a certain amount of vegetative structure, and then they will flower.”

Nature lovers would be wise to visit the columbo at the garden before it dies, because there’s no telling when the next one could bloom.