Where does “plaintain” come from?

plaintain (Old French) comes from Latin plantāgō, from Latin planta, from Proto-Italic plāntā, from Proto-Indo-European pléh₂-n̥t-eh₂, from Proto-Indo-European pleh₂- — flat.

Ancestry of “plaintain”, step by step

Step	Language	Word	Meaning
1	Latin	plantāgō	—
2	Latin	planta	any vegetable production that serves to propagate...
3	Proto-Italic	plāntā	—
4	Proto-Indo-European	pléh₂-n̥t-eh₂	—
5	Proto-Indo-European	pleh₂-	flat

Every word from Proto-Indo-European pleh₂- →

plaintain — Etymology, Origin & Word History | Etymology Explorer