Evolution is often depicted as a steady forward march from simple to complex forms. But new research shows that certain ferns can evolve ‘backward.’

Evolving, but not always forward

Ferns have multiple reproductive strategies. Most species combine spore development and photosynthesis on a single leaf type – a strategy called monomorphism. Others separate these functions to have one leaf type for photosynthesis and another for reproduction – a strategy called dimorphism.

Within a family known as chain ferns (Blechnaceae), we found multiple cases in which plants had evolved highly specialized dimorphism, but then reverted to the more general form of monomorphism.