Poisonous Plants: (1) Poison oak has leaves that look like oak leaves, usually with three leaflets but sometimes up to seven leaflets. It grows as a vine or a shrub. (2) Poison sumac has 7 to 13 leaflets per leaf stem. The leaves have smooth edges and pointed tips. It grows as a shrub or small tree. It is found in wooded, swampy areas. (3) Poison ivy usually has three broad, spoon-shaped leaves or leaflets, but it can have more. It may grow as a vine that sprawls through grass or as a shrub.