Staghorn Sumac is not poison Sumac. It has leaves with serated edges, fuzzy branches and a “Staghorn" in the fall (see the first image below) Poison Sumac has smooth edged leaves, no fuzz and white berries. It mainly grows in swamps. I’ve never actually seen poison Sumac. But definitely don’t gather any kind of Sumac in a swamp.

Pruned Staghorn Sumac found by the roadside. The Staghorns are a good source of tannin for dyeing or mordanting.

Between the tannin’s in the sumac and the iron in the water hands can temporarily turn a little purple if you don’t wear gloves.