High Quality Content by WIKIPEDIA articles! Aristolochia is a large plant genus with over 500 species. Collectively known as birthworts, pipevines or Dutchman's pipes, they are the namesake of the family (Aristolochiaceae). They are widespread and occur in the most diverse climates, but they are not native to Australia. Some species, like A. utriformis and A. westlandii, are threatened with extinction. Isotrema is usually included here, but might be a valid genus. If so, it contains those species with a three-lobed calyx.