I'm closer to an ID for this fern than I expected. It's in the Greig Rhododendron Garden, has surely been planted as an ornamental. I have three contenders for names: Athyrium filix-femina ‘Vernoniae Cristatum’? Or Athyrium filix-femina 'Corymbiferum'? Or Dryopteris filix-mas 'Crispa Cristata'? I don't know what the distinguishing characteristics are. I'm leaning toward the first one, based on an internet photo. The page at Dryopteris filix-mas 'Crispa Cristata' says "It is a good idea to put Dryopteris (male ferns) near Athyriums (lady ferns) for reasons that (I hope) are obvious." That doesn't seem obvious to me - unless the reason is for people like me who would like to compare them. Would they cross-fertilize and produce hybrids, or not cross-fertilize at all?