The most important weeds to identify are those that will cause you harm if you touch them or even brush up against them. These are typically poison ivy, poison oak and poison sumac. All three of these plants contain sap called urushiol that causes irritation, rashes, blisters and itching in humans. It's important to learn to identify these three plants so that you may know to handle them properly.

Identification

Poison ivy has a ropelike vine that is woody. The plant starts as a shrub in the ground and then wraps around nearby plants or structures. The plant normally has three leaflets, or three leaves all coming off the same stem, but the number of leaves can vary anywhere from three to nine. In the summer, the leaves are green; in the fall, they are red. Poison ivy blooms are yellow or green, and it produces white berries. Poison ivy can usually be found around lakes and streams in the Midwestern and Eastern United States.

Poison oak grows in shrubs in the East, from New England all the way down to Texas. Along the west coast, poison oak grows in clumps or huge vines, sometimes up to 30 feet long. The leaves look remarkably like leaves of an oak tree, with three different leaves coming off of one stem. Poison oak produces clusters of yellow berries.

Poison sumac usually grows in the Southeastern United States in boggy areas. Poison sumac grows in shrub form up to 15 feet tall. It has seven to 13 red and green leaves coming off of one stem. The berries of the poison sumac are pale yellow or cream colored.