Try to make your search as simple as possible:
Gibbaeum will find all items including that sequence of letters.
Search results for "Gibbaeum":
"Gibbaeum perviride" - Gibbaeum gibbosum
"Gibbaeum shandii" - Gibbaeum pubescens ssp. shandii
"Gibbaeum shandii K" - Gibbaeum pubescens ssp shandii Kareevlakte