Try to make your search as simple as possible:
Dyckia will find all items including that sequence of letters.
Search results for "Dyckia":
"Coryphantha salm-dyckiana" - Coryphantha delaetiana
"Dyckia Ladislaus Cutak" - Dyckia Lad Cutak
"Dyckia maritima" - Prionophyllum maritimum