Try to make your search as simple as possible:
Securinega will find all items including that sequence of letters.
Search results for "Securinega":
"Securinega buxifolia" - Flueggea tinctoria
"Securinega leucopyrus" - Flueggea leucopyrus
"Securinega ramiflora" - Flueggea suffruticosa
"Securinega tinctoria" - Flueggea tinctoria