Whether it is poison ivy or its cousin poison oak, either toxic plant is likely to leave those who come into contact with it headed for the great indoors. The irritation is actually caused by a toxic oil within the plant. Avoid the itching and rashes that often develop after encountering poison oak and poison ivy by knowing what to look for. Gardeners should also remember that both plants are poisonous every season of the year.
Identify poison ivy by its leaf type. Look for leaves that have three leaflets on each frond. According to the Missouri Department of Conservation, the center leaf of each leaflet is on a longer stem and the leaflets alternate along the stem rather than grow directly opposite each other. Look for greenish flowers that have five petals and fruit seeds that are hard and whitish in appearance.
Know the areas where poison ivy tends to grow. (The vine is commonly found growing along trees or other upright structures.) Be aware that poison ivy grows throughout all areas of the United States.
Know where poison oak commonly grows. (It grows as a shrub in the eastern part of the United States and as a vine along the Pacific Coast.)
Identify the leaves of poison oak which has a similar appearance to oak leaves and grows in clusters of threes. Look, too, for clusters of yellow berries and for hairs on young twigs and sometimes on the leaves.
Be aware of look-alikes such as Virginia creeper, common strawberry, black raspberry, box elder tree that are often mistaken for the toxic plants.