How To Recognize Poison Sumac

Learning how to recognize poison sumac is something I had to do recently.  I've lived in Missouri most of my life and suffered terribly with allergies to poison ivy and poison oak.  Now that I live in Maryland, how awful, we have all three poisons!  I have sensitive skin, so I blister terribly and I've already had it 3 times this year!  Identifying it was half the battle.  I had a hard time finding many pictures of Poison Sumac.
The first thing we did after moving in was cut down a sumac tree, due to the roots going into the foundation of our house.  Then I have all these plants popping up. I was worried about these and come to find out, they aren't even poisonous.  

This is NOT Poison Sumac.  It is a Staghorn Sumac. It has a hairy like stem and jagged leaves.
A very invasive plant.

 Identify Poison Sumac by leaves numbering 7 to 13 but who wants to stand that close and count anyway. The best way to tell is the smooth, bright red stem, then the smooth edge of the leaves and then the hanging white berries.

This is Poison Sumac.  It is growing about 10 feet away from the Staghorn Sumac.  The stems are smooth and so are the leaves. you can see red in the stems. 

Most websites I've been on, I read that poison sumac cannot grow in your yard because it usually grows in swampy, wetland areas.  The nearest water is a tiny creek at least 50 yards behind our house.  Notice the sandy ground, this plant gets shade so it is making it, this very hot summer in Maryland.  

Poison Sumac: Notice Red stem, hanging white berry/flowers and smooth leaves.

A smaller poison sumac tree. 

Another bright red stem!

This plant has the spot of sun on it and is starting to wilt because of our hot weather and lack of rain. 

Poison Sumac mostly grows in the northeast, the southeast, including parts of Florida, Georgia, Mississippi, Lousiana, and a small bit of Texas, the Carolina's and the Great Lakes Region of the United States.
  What luck, to live where all three poisonous plants grow!