It is not uncommon to come upon poison oak sinuously winding its way up the oak trees, or bushing out from the side of the road. We learned to spot poison oak early as kids. It has a distinctive look to it--even the bare branches. Most people are very allergic to it.
It is a beautiful plant, but the oils are VERY toxic. One only has to brush against a leaf with a coat sleeve. Until washed, the oils remain. Touch it days, or weeks later and soon the blistering, weeping and itching begin. Nasty stuff for all its beauty!
I am sure I must have brushed up against something in the woods not too long ago--I've been fighting poison oak for a week now. It got on my neck and into my eyes. Just today it seems to be a bit better ... hurrah for Calamine lotion!