Try to make your search as simple as possible:
Calpurnia will find all items including that sequence of letters.
Search results for "Calpurnia":
"Calpurnia antunesii" - Pterocarpus antunesii
"Calpurnia aurea ssp. aurea" - Calpurnia aurea
"Calpurnia intrusa" - Calpurnia villosa