Try to make your search as simple as possible:
Stellaria will find all items including that sequence of letters.
Search results for "Stellaria":
"Stellaria aquatica" - Myosoton aquaticum
"Stellaria edwardsii" - Stellaria longipes
"Stellaria grandiflora" - Arenaria grandiflora
"Stellaria uliginosa" - Stellaria alsine