Try to make your search as simple as possible:
Calochortus will find all items including that sequence of letters.
Search results for "Calochortus":
"Calochortus citrinus" - Calochortus luteus
"Calochortus Golden Orb" - Calochortus luteus
"Calochortus madrensis" - Calochortus exilis
"Calochortus v roseus" - Calochortus albus v rubellus