An oil called urushiol causes skin irritation when you brush up against this 3-leafed plant, Rhus radicans
Poison Oak is a low-growing shrub (up to 3 ft tall) with compound... [DOC] [TLE] Poison Ivy, Oak, and Sumac - symptoms, Definition, Description ... [PAR] All three plants secrete a potent, irritating oil known as urushiol that causes 
blistering ... brush against a plant can cause the urushiol to seep out and onto the 
skin.