The Plant List is not a reliable taxonomic source (too outdated and too full of errors), so I'm not surprised that they list H. flava as a synonym for H. fulva. Our database lists H. flava as a synonym for H. lilioasphodelus, which is the correct current status of the taxon.
The CoL entry for H. flava var. flava does list H. fulva as a synonym, but it also says "nom. illeg.," meaning that it was once listed as a synonym incorrectly.
http://www.catalogueoflife.org...
In contrast, the CoL entry for H. lilioasphodelus lists H. flava as a legitimate synonym.
http://www.catalogueoflife.org...
As for the 2001 research you cite, I can only assume that it was disproved in subsequent years.
