A genus (formerly part of rhus genus) of shrubs, vines, or trees that yields a highly allergenic oleoresin which causes a severe contact dermatitis (dermatitis, toxicodendron). The most toxic species are Toxicodendron vernix (poison sumac), T. diversilobum (poison oak), and T. radicans (poison ivy). T. vernicifera yields a useful varnish from which certain enzymes (laccases) are obtained.