Poison Oak

Poisonous

Poison oak (Toxicodendron diversilobum) is not an oak; nor is it technically poisonous. It has attractive leaves that are bronze when young in the spring, shiny green in the summer and gold and red in the autumn before they fall. It may be the most feared plant in California.
“Leaves of three, let it be”

Caution

The plant produces a substance, urushiol, that most people are allergic to. It produces an unbearable, itching, blistery, oozing skin rash that is “nothing more than the immune system gone haywire, fighting some harmless substance."

Only humans are bothered. Animals graze on the foliage with impunity, and many birds find the seeds a delicacy.