As a relative newcomer to the world of ferns, I'm struggling with the naming of one (or two) species of Dryopteris. The Fern in question is Dryopteris atrata. Some websites seem to suggest this is the new name for what was formerly known as Dryopteris cycadina. Other sites suggest it should be known as Dryopteris atrata Cycadina. Then to really throw me, a well known and trusted RHS publication has listed both as seperate species. Can anyone shed any light on the matter?