Poison sumac doesn't have just three leaves

[Carptracker]

http://www.straightdope.com/columns/read/2919/im-on-a-deserted-island-how-can-i-tell-which-plants-are-poisonous

From the text: "Also, remember: "leaves of three, let them be" — groups of three leaves being the sign of poison ivy, sumac, and oak."

Poison sumac has 9 to 13 leaflets usually on its compound leaf.

www.duke.edu/~cwcook/trees/tove4969.jpg

[Una Persson]

You are of course correct, and I notified folks to make sure that the column was updated. The explanation I heard was that a copy editor down the line had a moment of brief confusion, which rippled through the fabric of reality and caused the vacuum to spawn forth an extra word (and a corresponding anti-word, which ended up over at Fox News and ate a hapless web designer, if I recall correctly). Hazards of the business, they say.