birthwort n creeping plant having curving flowers thought to resemble fetuses; native to Europe; naturalized Great Britain and eastern North America Usage(s) The list: aristolochic acid (birthwort), comfrey, germander, androstenedione, chaparral, kava, bitter orange, organ or gland extracts, lobelia, pennyroyal oil, scullcap and yohimbe. The list: aristolochic acid (birthwort), comfrey, germander, androstenedione, chaparral, kava, bitter orange, organ or gland extracts, lobelia, pennyroyal oil, scullcap and . The highly toxic herb is likely to be present in a host of botanicals, including Dutchman's pipe, guan mu ton, heart snake root and birthwort. Synonym(s) Aristolochia clematitis