By Maddy Rohr, K-State Research and Extension news service
Manhattan, KS. — Poison ivy and Virginia creeper are different in appearance during the growing season because of their leaflet patterns, but are much more similar in the winter when they have dropped their leaves, which begs the question: Why should we care?
“The reason it is important to be able to tell the difference is that poison ivy causes a rash in most people, but Virginia creeper does not,” said Kansas State University horticulture expert Ward Upham.
Urushiol is the oil present in poison ivy that causes the rash, Upham said. Urushiol is present in all parts of the plant but especially in the sap and can cause a rash from 1-5 years after a plant has died.
“The amount of urushiol that covers the head of a pin can cause a rash in 500 people. The stuff is potent,” Upham said.
Poison ivy can grow as a ground cover, a shrub or a vine, but the vine is the most similar in appearance to Virginia creeper, Upham said.
To tell the vines apart, look at the aerial roots on the vines of poison ivy and Virginia creeper.
“They resemble hairs on poison ivy but are plumper on Virginia creeper and are about the size of a pencil lead,” Upham said.
Upham and his colleagues in K-State’s Department of Horticulture and Natural Resources produce a weekly Horticulture Newsletter with tips for maintaining home landscapes and gardens. The newsletter is available to view online or can be delivered by email each week.