Poison ivy has a restricted presence in Arizona compared to other regions of the United States. The species found here is primarily Western Poison Ivy (Toxicodendron rydbergii), not the Eastern Poison Ivy (Toxicodendron radicans) common elsewhere. While not widespread, this plant does exist in specific Arizona environments, meaning residents and visitors should still be aware of its potential presence.
Where Poison Ivy Grows in Arizona
Poison ivy in Arizona is largely confined to habitats providing moisture and shade, unlike the state’s arid landscape. It is commonly found in riparian areas, which are lush zones alongside rivers, streams, and other bodies of water. Canyon bottoms and higher elevation, moist, shaded environments also provide suitable conditions. These locations, particularly in central and northern Arizona, such as along the Mogollon Rim, offer the consistent water sources and protection from intense sun the plant needs to flourish.
Recognizing Poison Ivy
Identifying poison ivy involves observing distinct characteristics. Its most well-known feature is compound leaves, always consisting of three leaflets. The middle leaflet typically has a longer stem than the two side leaflets. Leaflet edges can vary, appearing smooth, lobed, or with jagged teeth.
Poison ivy leaves also change color seasonally, appearing reddish in spring, green in summer, and shifting to yellow, orange, or red in fall. The plant grows in different forms, including a vine with “hairy” aerial roots, a shrub, or as ground cover. Small, whitish-green berries may also be present, especially in fall.
Look-Alikes
Several Arizona plants are often mistaken for poison ivy but do not cause a rash. Virginia creeper (Parthenocissus quinquifola) is a common look-alike, typically having five leaflets, though young plants might occasionally have three. Unlike poison ivy’s hairy vines, Virginia creeper vines are smooth and climb with adhesive discs.
Box elder (Acer negundo) is another plant sometimes confused with poison ivy, especially when young, as it can also have three leaflets. A key difference is that box elder leaves are arranged oppositely on the stem, while poison ivy leaves are arranged alternately. Box elder can also grow into a sizable tree, unlike poison ivy which remains a vine, shrub, or ground cover.
What to Do After Contact
If contact with poison ivy is suspected, immediate action can reduce the rash’s severity. The rash is caused by urushiol, an oily resin found in all parts of the plant. This oil can transfer from the plant to skin, clothing, tools, or pet fur.
Wash affected skin with soap and lukewarm water as soon as possible, ideally within minutes, to remove the urushiol. Cleaning under fingernails is also recommended. All clothing and items that contacted the plant should be washed thoroughly to prevent further spread.
Symptoms and Treatment
Symptoms of a poison ivy rash include an itchy, red rash with swelling and fluid-filled blisters. The rash appears 12 to 48 hours after exposure and can last for two to three weeks. Avoid scratching, as it can lead to skin infection.
For mild cases, home remedies like cool compresses, lukewarm baths with colloidal oatmeal or baking soda, and applying calamine lotion or hydrocortisone cream can relieve itching. Seek medical attention if the rash is severe, widespread, affects eyes, mouth, or genitals, shows signs of infection (like pus or fever), or if itching is intense and disrupts sleep.