Where does “*petrosilium” come from?

*petrosilium (Vulgar Latin) comes from Latin petroselīnum, from Ancient Greek πετροσέλινον, from Ancient Greek Πέτρος, from Ancient Greek πέτρος — rock, stone, boulder; type of reed.

Ancestry of “*petrosilium”, step by step

Step	Language	Word	Meaning
1	Latin	petroselīnum	rock parsley
2	Ancient Greek	πετροσέλινον	parsley
3	Ancient Greek	Πέτρος	Peter
4	Ancient Greek	πέτρος	rock, stone, boulder; type of reed

Every word from Ancient Greek πέτρος →Every word from Ancient Greek Πέτρος →Every word from Ancient Greek πετροσέλινον →