Try to make your search as simple as possible:
Vicoa will find all items including that sequence of letters.
Search results for "Vicoa":
"Lucuma rivicoa" - Pouteria macrophylla
"Lucuma rivicoa var. angustifol" - Pouteria campechiana svs
"Richardella rivicoa" - Pouteria macrophylla
"Vicoa indica" - Pentanema indica