The term POISONOUS SHRUB refers to two plants, Oleander (8 letters) and SUMAC (5 letters). Oleander is a flowering shrub native to the Mediterranean region that has become an invasive species in many parts of the world. All parts of the plant are toxic and can cause severe illness or death if ingested. SUMAC is a genus of flowering plants in the family Anacardiaceae, which includes poison ivy and poison oak. All parts of the plant are toxic and can cause skin irritation and other symptoms if touched.