As I showed in the research, in the 19th century "Maud Irving" was a two-word given name, like Ann Marie or Peggy Sue, not a first name and last name, and it was used as such in works of fiction.

Personally, I use the lyric the pale amaryllis and [the] hyssop so blue, not because there's any historical justification for doing so, but because (1) there really is a pale amaryllis, (2) the hyssop flower really is "so blue," (3) it's at least conceivable that hyssop so blue could have resulted in the mondegreen eyes of bright blue of Wildwood Flower because of its similarity in sound, and most importantly (4) I think it sounds better. :-)