Yes, poison ivy is present in Colorado, though the specific variety and its growth habit differ from the familiar climbing vine found in eastern states. The plant is a native species that contains the same allergenic oil, urushiol, which causes an irritating skin rash upon contact. Understanding the local growth patterns and preferred habitats is key to avoiding exposure in Colorado’s diverse landscapes.
Where Poison Ivy Grows in Colorado
The variety of poison ivy common to Colorado is Western Poison Ivy (Toxicodendron rydbergii), which exhibits a shrub-like form rather than the climbing vine of its eastern counterpart. This species is frequently encountered in the foothills, canyons, and along the eastern plains of the state. Its presence is strongly tied to water sources, making riparian areas along rivers, streams, and seeps its preferred habitat.
The plant’s distribution is limited by elevation and moisture availability, but it can be found in montane communities up to around 8,500 feet. It is significantly less common in the higher, drier mountains or in dense coniferous forests. You will often find it in disturbed sites, such as trail edges, fence rows, and the bases of cliffs, where it can form dense thickets.
Identifying the Colorado Variety
Identifying the Colorado variety requires recognizing its specific morphology, which often presents as a low-growing shrub or small bush, typically under three feet tall. It rarely forms the large, climbing vines associated with the Eastern species. The plant adheres to the well-known “leaves of three” structure, where each leaf consists of three leaflets. These leaflets are alternate on the stem and can vary in shape, often appearing somewhat almond-shaped or egg-shaped with pointed tips.
The leaves may be glossy or dull and can have smooth, notched, or slightly toothed edges. Seasonal color changes are a distinctive feature; new leaves often emerge reddish-maroon in spring and turn brilliant red, orange, or purple in the fall. In late summer and fall, female plants produce small, round, white berries that may persist into the winter. Even the bare stems in winter are hazardous because the urushiol oil remains active in all parts of the plant year-round.
Immediate Response to Contact
When skin contact occurs with poison ivy, the oily resin urushiol begins to bind to the skin cells, requiring immediate action to mitigate the allergic reaction. The most effective step is to wash the exposed area with lukewarm water and soap as soon as possible, ideally within the first 10 to 20 minutes. This washing should be gentle and repeated multiple times to remove the sticky oil. If soap is unavailable, alcohol-based wipes can help dissolve and remove the oil.
Washing contaminated clothing, gear, and a pet’s fur is also necessary, as the oil can remain active on surfaces and cause secondary exposure. Once a rash develops, over-the-counter treatments like calamine lotion, hydrocortisone creams, or cool compresses can help reduce the intense itching and inflammation. Severe reactions, such as those involving significant swelling, a rash covering a large portion of the body, or any rash near the eyes, mouth, or genitals, require prompt medical attention.