Where does “jonc” come from?

jonc (Middle French) comes from Old French jonc, from Latin iuncus, from Proto-Italic joinikos, from Proto-Indo-European yoy-ni-.

Ancestry of “jonc”, step by step

Step	Language	Word	Meaning
1	Old French	jonc	rush
2	Latin	iuncus	rush, reed
3	Proto-Italic	joinikos	—
4	Proto-Indo-European	yoy-ni-	—