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'Weird' Fern Shows The Power Of Interspecies Sex

Botanists say this plant is the fern equivalent of a human-lemur love child.
Harry Roskam
Botanists say this plant is the fern equivalent of a human-lemur love child.

The love between two ferns knows few bounds, it appears. A DNA analysis of a hybrid fern shows that its parents are two different species separated by nearly 60 million years of evolution.

"A 60 million year divergence is approximately equivalent to a human mating with a lemur," says Carl Rothfels, a fern researcher at the University of British Columbia, who headed the study. The hybrid is a record, he says.

The freak fern, known as Cystocarpium roskamianum,isn't rare. It can be found spreading its fronds across the French Pyrenees. You can even buy it at some European garden centers, Rothfels says.

But fern researchers have always thought it looked sort of weird.

"I mean, on one level it looks like a fern," Rothfels admits.

But he says this type of fern appears to have come from two parents that you wouldn't expect to be a couple. One lives on rocky outcrops. The other is found on the floors of forests. They are two different species from different places, and yet somehow they get together to make this hybrid.

"It is pretty much exactly between the two parents," he says

The team's DNA analysis confirming the odd coupling is published in the March edition of the journal The American Naturalist.

"Ferns are unique among plants for many reasons, and this study adds another potential difference to the list," says Emily Sessa, a researcher at the University of Florida in Gainsville. Apparently, ferns do not easily evolve barriers that keep them from interbreeding.

That flexibility could help explain why there are only 10,000 species of ferns on the planet, as opposed to some 250,000 species of flowering plants, adds Robbin Moran, curator of ferns at the New York Botanical Garden.

Rothfels says the hybrid fern is sterile, though it can reproduce "vegetatively" by sending out runners across the ground.

"It seems to be quite happy," he says.

Copyright 2021 NPR. To see more, visit https://www.npr.org.

Geoff Brumfiel works as a senior editor and correspondent on NPR's science desk. His editing duties include science and space, while his reporting focuses on the intersection of science and national security.