petro-, petr-, petri-, peter-

In biology, thriving on rocks or in rocky habitats.

Of or related to parsley.

A stratum of sedimentary or igneous rock that produces, contains, or is impregnated with salt.

1. Potassium nitrate; used especially as a component of gunpowder or as a food preservative.
2. Etymology: Saltpeter is a borrowing of Old Middle English salpetre [about A.D. 1300]; a borrowing of Old French, salpetre, a learned borrowing from Medieval Latin; also borrowed directly from Medieval Latin sal petrae, "salt of rock"; from Latin sal, "salt" + petrae, genitive form of Latin petra, "rock".

So called because it appears as a salt-like encrustation on rocks.