Aristolochiaceae: A plant family of the order Aristolochiales subclass Magnoliidae class Magnoliopsida. They are mostly tropical woody vines and a few temperate-zone species. The flowers are 3-parted; some species lack petals while others are large and foul smelling.Aristolochia: A plant genus of the family ARISTOLOCHIACEAE. Species of this genus have been used in traditional medicine but they contain aristolochic acid which is associated with nephropathy. These are sometimes called 'snakeroot' but that name is also used with a number of other plants such as POLYGALA; SANICULA; ASARUM; ARISTOLOCHIA; AGERATINA; and others.