Try to make your search as simple as possible:
Rafnia will find all items including that sequence of letters.
Search results for "Rafnia":
"Rafnia axillaris" - Rafnia elliptica
"Rafnia ovata" - Rafnia amplexicaulis
"Rafnia perfoliata" - Rafnia acuminata
"Rafnia retusa" - Templetonia retusa prov. WA