Sagittaria sagittifolia
From LSJ
ὃν οὐ τύπτει λόγος οὐδὲ ῥάβδος → if words don't get through, neither a beating will | if the carrot doesn't work, the stick will not work either | whom words do not strike, neither does the rod
Translations
Bulgarian: стрелолист; Catalan: sagitària; Chinese Mandarin: 慈姑; Czech: šípatka; German: Pfeilkraut; Hungarian: nyílfű; Japanese: 慈姑; Korean: 벗풀; Latin: sagitta; Navajo: táłkááʼbéésh; Portuguese: sagitária; Romanian: săgeata-apei, săgeata-apelor; Russian: стрелолист; Umatilla: ɨstíˀɨstins
