Heres something I found....
All About Sumac
by Sandra Bowens
If you are like most people, when you hear the word "sumac" the first thing that comes to mind is poison. It is a good idea to be wary of poison sumac, also known as poison oak, but you have nothing to fear from sumac the spice.
Although the two are related, sumac the spice is derived from the berry of a plant called
Rhus coriaria. The name refers to the word
corium, Latin for leather, as the leaves and bark are used in the tanning process. This shrubby tree grows wild in the Middle East and parts of Italy. The brick-red fruits are sold as dried coarsely ground or whole berries. The spice is also known as "Sicilian sumac," "sumaq" or "sumach," and other similar variations.
Rather tart and astringent in taste, sumac is often referred to as a "souring agent." It was once used to calm the stomach. Today sumac is considered mainly a condiment used much like salt in that it is passed in small dishes at the table. The spice is tasty on grilled meats and fish or as a seasoning for rice. It complements lentils and other beans as well as vegetables. "Try seasoning a thinly sliced onion with 2 tsp. of sumac," suggests the latest
Penzey's Spices catalog.