The Clayton or Interrupted Fern seems very cool... I like the bright green color and the wooly fronds coming up.

By what little info I find to read that it is a "primitive" fern, the Osmundo genus being related to ferns dating back before the more modern spore bearing ferns came on the scene, though I haven't found any more specific info on that. One site said that it is recorded in the fossil record for 200 million years. The Royal Fern must be similar in age, spread all over the different continents...

My questions...

Why do fronds come up all sterile and normal on some plants, then another plant all the fronds are fertile with the interruption, then another plant has a mix of the two types of fronds? I'm not sure what happens in nature... does this have anything to do with age or conditions?

How far will one planting spread in five years in a decent soil but mostly shade?

Thanks