Western Poison Ivy (Toxicodendron Rydbergii)

Identifying Western Poison Ivy

Colorado trailheads often warn about western poison ivy being near the trail and especially near moist river banks. Western poison ivy (Toxicodendron Rydbergii) is a perennial shrub in the Cashew family. Western poison ivy typically has almond shape leaves, red veins, and yellowish-white berries. Three important notes about wester poison ivy are 1) not all of the leaves on a poison ivy plant have ridges, 2) the leaves are usually but not always in leaflets of three leaves (i.e., trifoliate), and 3) during autumn the leaves turn red. Finally, each poison ivy shrub is capable of growing to be nine feet tall. The following pictures show western poison ivy plants from varying distances and angles.

Poison Ivy Symptoms and Treatments

Western poison ivy plants secrete a milky oil called Urushiol that in liquid form or as dried residue can cause severe skin irritation (i.e., Urushiol-induced contact dermatitis). Specifically, poison ivy can cause severe skin rashes, blisters, fevers, headaches, and itching. If you think poison ivy oil or residue got on your skin then you want to immediately wash the affected area with soap, water, and/or alcohol. In addition, calamine lotion can be used to reduce itching.

If you hike with kids, please download and print our free PDFs: Poison Ivy Field Guide and Hiking Checklist for Kids.