For the most part, the groups are families. “We quickly realized the genetics is important,” Dr. Burns said, because eusocial animals live in closely related groups.
When researchers analyzed DNA from 11 fern colonies, they found that most plants within a colony were as closely related as possible: They were clones. New plants arise from buds in the root systems of others, Dr. Burns said.
Being clones “means that the different individuals have aligned interests genetically,” said Guy Cooper, an evolutionary biologist at the University of Oxford. By helping a neighboring clone, a plant is also helping its own genes survive.
Dr. Cooper said he would like to know more about the life cycle of a colony, and how much the individual ferns depended on one another.
Even if staghorn ferns aren’t as social as bees, “it was very cool to see that there might be similar sorts of complex social behaviors happening in plants,” he said.
He also pointed out that some plants that spread by cloning themselves were considered to be one individual, not many. For example, aspen trees sprout massive groves of clones from one root network. An aspen forest in Utah nicknamed Pando is sometimes called the world’s largest single organism, covering 106 acres.
“You then have to wonder about some more philosophical questions about whether they are different individuals to start with,” Dr. Cooper said of the ferns. Maybe the ferns within a colony are more like limbs on a body than bees in a hive.