The three main types of plants that cause Rhus dermatitis vary in both their appearance and geographic location.
- Poison ivy leaves are most often notched on the edges and arranged in groups of three (although some varieties are smooth-edged). Poison ivy is usually found east of the Rocky Mountains as either vines or shrubs.
- Poison oak leaves grow in groups of either three, five, or seven. The leaves are smaller than poison ivy and have smooth, rounded edges. Poison oak is usually found west of the Rocky Mountains as a small bushy plant or climbing vine.
- Poison sumac has seven to thirteen leaves on one stem pointing at an upward angle. They are oval, smooth-edged, and about 10 centimeters long. Poison sumac is found in boggy areas of the South.