Try to make your search as simple as possible:
Muehlenbeckia will find all items including that sequence of letters.
Search results for "Muehlenbeckia":
"Muehlenbeckia adpressa v hast." - Muehlenbeckia gunnii
"Muehlenbeckia cunninghamia" - Muehlenbeckia florulenta
"Muehlenbeckia platyclada" - Homalocladium platycladum