Scientists Uncover New Leads on Plant Evolution

Scientists from Harvard have found new information that could explain the evolution of the world’s largest flower, the Rafflesia arnoldii. Long considered an enigma by botanists, the Rafflesia arnoldii is characterized its oversized red, speckled petals and a unique odor of decaying flesh.

According to a study published in late October in the journal Proceedings of the National Academy of Sciences, a group of Harvard researchers have gained insight into the evolutionary origin of the Rafflesiaceae family of plants.

“The Rafflesia is such a strange and unique flower,” said Lachezar Nikolov ’07, a postdoctoral degree candidate in Cologne, Germany. “It was so mysterious that even though it was discovered a long time ago, people didn’t know what’s the organ identity of the different flowering parts of this flower.”

In order to solve that question, Nikolov collected Rafflesia samples from the rainforests of Southeast Asia and compared the specimens with a relative flower, the Sapria. Nikolov and his colleagues found that although these two types of flowers shared similar qualities, their commonalities were encoded by different genes.

“These results came as a surprise to us,” said Charles Davis, an Organismic and Evolutionary Biology professor who co-authored the study. “We had thought that something went wrong in the tests, but the more we tested, the more likely it seemed.”

“These results suggest that the similar characteristics of the Rafflesia and Sapria didn’t come from the same evolution,” said Elena M. Kramer, Davis’s colleague in the OEB department and another co-author of the study.  “It suggests that these species morphed independently from each other.”

Nikolov said he hopes that the researchers’ discovery will draw more attention to the Rafflesia.

Botany professor and Interim Dean of the College Donald H. Pfister took a particular interest in the new findings—Pfister served as Kirkland House Master during Davis’s time as a tutor and signed off on Davis’ graduate thesis.

“It’s a cool paper,” Pfister said. “You end up with the same result, but they’re different developmental patterns. As soon as you tell people that there are flowers like this, they begin to connect with it [plant evolutionary biology]."

The results of the study can also serve as a life lesson, Kramer said.

“I think this is a reminder about the surprising direction that evolution can take,” Kramer said. “Instead of it being the simplest answer, the truth can be more complicated than that.”