It's always a good day when ferns make the news, so the last few weeks have been pretty great! Carl Rothfels and colleagues have determined that two ferns alive today, but whose ancestors diverged from one another around 60 million years ago, have hybridized to form a new (although sterile) species. The new species is a hybrid between two different genera, Cystopteris and Gymnocarpium, and its name is Cystocarpium roskamianum. Intergeneric hybrids are very rare, because it becomes more and more difficult to be interfertile the more diverged two organisms are from one another. We often consider species to be units that are distinct from one another reproductively (although this is frequently untrue, particularly in plants), and genera are implicitly assumed to be even more so. There are four other known intergeneric hybrids in ferns, including Dryostichum singulare, a hybrid between Dryopteris goldiana and Polystichum lonchitis, but none involve parental genera as anciently diverged as Cystocarpium's. The authors use the analogy that this would be like a human and a lemur mating and producing offspring – the genetic distances involved are similar!
The story has been covered by a number of news outlets. Links are below, and I'm pleased to add that I was contacted for a comment for the NPR piece, which I very happily gave.