Try to make your search as simple as possible:
Guarea will find all items including that sequence of letters.
Search results for "Guarea":
"Guarea africana" - Turraeanthus africanus
"Guarea binectarifera" - Dysoxylum binectariferum
"Guarea guara" - Guarea guidonia
"Guarea rusbyi" - Guarea guidonia
"Guarea trichilioides" - Guarea guidonia