poison ivy
(ī'vē 
)
A climbing vine, Toxicodendron radicans, that on contact may produce severe pruritic dermatitis. Toxicodendron species contain urushiol, an extremely irritating oily resin, which stimulates a hypersensitivity reaction. First contact produces sensitization; later contacts cause severe blistering, eczema, and itching.
SEE: poison ivy dermatitis .