Toxicodendron radicans, commonly known as poison ivy (older synonyms are Rhus toxicodendron and Rhus radicans), is a poisonous North American and Asian plant that is well known for its production of urushiol, a clear liquid compound found within the sap of the plant that causes an itching, irritation and sometimes painful rash in most people who touch it. The plant is not a true ivy (Hedera).