The allopolyploid origin of D. dilatata was demonstrated more than 30 years ago using experimental hybridization and the study of chromosome pairing behaviour. I'm currently doing some work in China and cannot delve into my library to come up with the "right" litterature. I guess D. camyloptera and D. dilatata share the same genome but originated independently. Any "news" on that aspect?

Ron - 

If I remember correctly, the work by Sigel confirmed earlier work that demonstrated parallel origins for the two allopolyploids, and provided insight into the historical biogeography of the complex. I think a key insight from her work was that contributor of the "D. intermedia" genome to D. dilatata was uncertain, and that it was genetically distinct from typical D. intermedia (which contributed the genome to D. campyloptera). 

The earlier work should also be relevant to Mr. Larsson's work. 

Thanks for the message. 

Wes 

Ron and Wes,

Emily Sessa's works iin 2012 are relevant

Reticulate evolution on a global scale: A nuclear phylogeny for New World

Dryopteris (Dryopteridaceae), MPE 

Sessa 2012_Unraveling reticulate evolution in North American Dryopteris (Dryopteridaceae), BMC Evolutionary Biology

Best wishes, Libing