mesembryanthemum
noun
me·sem·bry·an·the·mum mə-ˌzem-brē-ˈan(t)-thə-məm 
: any of a genus (Mesembryanthemum) of chiefly southern African fleshy-leaved herbs or subshrubs of the carpetweed family
Word History
Etymology
New Latin, irregular from Greek mesēmbria midday (from mes- + hēmera day) + anthemon flower, from anthos — more at anthology
First Known Use
1753, in the meaning defined above