Edible sumacs are botanically related to cashews and mangoes, so those with allergies to them should also avoid sumacs. Edible sumacs are also related to poison sumac (Rhus vernix), which has drooping, white berry clusters and shiny leaves. Poison sumac can produce rashes and itching in people with a sensitivity, and should be learned so you can avoid it. We don't often encounter poison sumac, as it prefers a wetter environment than the edible sumacs, like swamps.
|smooth sumac berries|
Here's a link of Russ Cohen discussing sumac late last autumn.
|smooth sumac ripe berry heads|