Ferns are very old plants that long predate ... heart-shaped plants known as prothallus are formed. These tiny plants attach themselves to the soil by rhizoids, which are single-celled, hairlike ...

Fern sex is not some flowery business with bees ... After tweaking by the recipient prothallus, it’s the same gibberellin molecule that’s active in seed plants, Sun notes.

Interestingly, all other living ferns produce just one type of prothallus, not separate male and female forms. It is this degree of specialisation that makes the nardoo genus, Marsilea ...