The Aristolochia genus is particularly close to the heart of the Manchester Herbarium, its name provides us a unique Twitter nom de plume. But it is also a plant with a considerable body count. It contains a carcinogen which may be responsible for a larger number deaths than more notorious plant poisons like cyanide and ricin.
A number of species in the Aristolochia genus are known as birthwort. The genus name is derived from the Greek for “good for childbirth”, so both the common and scientific names suggests its medical use. It was noted by Roman doctors that the flowers of Aristolochia clematitis were somewhat womb-shaped. The Doctrine of Signatures, a major concept within the medicine of the time, stated that plants were designed to resemble the body part they could treat. Therefore A. clematitis roots were used for over two thousand years to trigger delayed menstruation, speed up a labour and help deliver a placenta. The plant continues to be used in Traditional Chinese Medicine and more rarely in homeopathy to treat a wide variety of diseases, despite the risks.
The roots of all Aristolochia sp. contain the carcinogen aristolochic acid, which for anyone can produce more mutations in the genome than tobacco smoke or UV light, but in the 5-10% of people who are genetically susceptible can cause kidney and urinary tract cancers. This was discovered when, in the late 1950s, localised epidemics of kidney disease and urinary tract cancer in certain rural villages in Bulgaria, Yugoslavia and Romania were noted. The condition was described as Balkan Endemic Nephropathy (BEN) but it’s cause was not found. However, in the 1990s a group of women with End Stage Renal Disease were all found to have taken the same herbal mixture for weight loss contaminated with Aristolochia fangchi, and their condition was described by researchers as Aristolochic Acid Nephropathy. When Prof Arthur Grollman from Stony Brook University learned this, he saw the similarities with BEN, and wondered if there was a similar cause. He found A. clematitis in the wheat fields of affected villages and the imprint of aristolachic acid damage in the DNA of BEN patients’ kidneys cells, showing a causal link between chronic exposure to Aristolochia and these cancers.
Aristolochia has been taken by many people as medicine or accidentally throughout history. As recently as between 1997 and 2003, an estimated 8 million people in Taiwan, were exposed to it in herbal medicine. This has lead some to suggest that it may be the most deadly plant in terms of number of fatalities rather than outright toxicity. Whether or not this claim could be quantified, it highlights that plants can be dangerous if used unwisely, so herbal medicines should not be taken blithely.
A. clematitis itself is a common weed, with creeping rhizomes and cordate (heart shaped) leaves. The distinct yellow flowers lack petals and form a tubular structure with a rounded base. Hardly notably uterine. The strange shape of the flower is due to it’s peculiar method of pollination. The hermaphroditic flowers begin first with the female stage and attract and trap flies within the flower, where they feed and spread pollen. In a few days the male stage produces the pollen that covers the trapped flies, which are released to pollinate again.
The native range is around the Mediterranean into central Europe, but was cultivated in the UK and USA. In the UK, it can be found as the survivors of the medicinal gardens of ruined nunneries and monasteries, a reminder of health care’s past and present mistakes.
For more information, see: