How many leaves does poison oak have?

Clusters of poison oak have three leaves each, just like poison ivy. However, the edges of poison oak leaves have a similar shape to oak leaves but with crimping around the edges.

Most frequently, poison oak grows as a shrub, but it also appears sometimes as a vine, usually winding its way around larger plants and trees. People who touch poison oak tend to develop a red rash between 12 and 72 hours after contact. The ingredient that causes the itch is urushiol, an oil in the roots, stems and leaves of the plant. Avoid touching someone who has touched poison oak because the oil can be spread through indirect contact and can be enough to cause a rash.