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The Fascinating World of Ferns with Dr. Sessa

By Patrick Sherry

Associate Professor of Biology at the University of Florida Dr. Emily B. Sessa cuts open plants to reveal their beautiful and intricate structures and patterns to understand the evolutionary history of plant biodiversity.

Focusing primarily on ferns, the Sessa Lab’s projects research the biological mechanisms that shape the evolution of different plant species. Ferns, unlike flowering plants, do not produce fruits or flowers but rely on spores to reproduce. These spores are carried by the wind to spread the next generation of ferns to new areas. Not only that, but ferns also play a vital role in ecosystems due to their ability to somewhat control forest regeneration, act as ecosystem engineers, and provide habitats for other plants and animals. These significant roles are often overlooked because they may not be highly visible aspects of the world.

photo by Alan Cressler: Sessa standing in a cypress dome in Big Cypress National Preserve.

Sessa became interested in plants at a young age because of their beautiful colors, shapes, and patterns. Since then, she received a Ph. D from the University of Wisconsin, received tenure from UF, won several awards, and gained notable recognition for her research in the field.

“I want to study something every day that I think is beautiful, interesting, and fun – ferns just check all the boxes for me,” said Sessa.

photo courtesy of Dr. Emily B. Sessa: Dr. Sessa’s research on ferns studies the different mating systems that exist among fern species such as homosporous land plants. This research has led to collaborations with other scientists in the field.

One of the main methods her lab uses is researching phylogeny, the study of the history of the evolution of species.

“You’ve probably heard the famous saying that ‘nothing in biology makes sense except in the light of evolution,’” said Sessa. “And evolution is phylogenies; what evolution is, how you can depict evolution visually is by using a phylogenetic tree. I absolutely would support the reinterpretation of that statement to be ‘nothing in biology makes sense except in the light of phylogeny.’”

By building phylogenies, or family trees, for different groups of organisms, researchers are able to accurately trace the ancestry of species and learn about their similarities and differences.

Her lab offers many opportunities for undergraduate and graduate students to learn and begin research in the field, which she says is one of the best aspects of her job.

Furthermore, throughout her research career, Dr. Sessa has made many academic accomplishments.

She believes her biggest accomplishment thus far is receiving the 2019 Emerging Leader Award given by the Botanical Society of America. This award recognized Sessa’s influential scholarship and service to botanical sciences.

In 2019, Sessa and her team received a $1.2 million grant from NASA to study a phenomenon called the fern spore spike. Following the K-PG mass extinction event, ferns were one of the first species of species to adapt to the new ecological changes in the environment, leaving evidence of this in the fossil record. Her team is investigating how ferns were able to succeed after this mass extinction event. This research can potentially be applied to current environmental issues experienced on Earth.

photo by Alan Cressler: Sessa photographing a rock-dwelling lycophyte (a clubmoss) in North Carolina.

Her latest academic pursuit is writing a book. In the summer of 2020, Sessa received an offer to write a field guide for ferns and lycophytes of eastern North America from the Princeton University Press. For this book, she is providing updated research and information made possible through recent advances in technology and science.

Overall, Sessa and her lab’s research are efforts to better understand the planet’s biodiversity and to potentially uncover uses for humanity.

“Just from the perspective of loving knowledge and thinking that knowledge has value in of itself – I am a very strong proponent of the idea of discovery for the sake of discovery,” said Sessa. “You never know what we might learn.”