Guest Post by Laura Cooper
The Hours of Jeanne de Navarre is one of the most famous and beautiful illuminated manuscripts. It is a collection of prayers and psalms for each of the hours of the medieval religious day made for the personal use of the Queen of Navarre somewhere between 1328-1343. The book is lavishly and elegantly decorated with images of saints and angels framed by a naturalistic border. This curling foliage has been referred to as ivy, but was identified by Christopher de Hamel actually white bryony, Bryonia dioica.
Bryony is a notoriously poisonous plant, so the scenes the illuminator painted are far from idyllic. As de Hamel writes in his book Meetings with Remarkable Manuscripts,“The world in the medieval margins is not a comfortable place, any more than the gilded life of Jeanne de Navarre was safe and secure.” Bryony is not just a decorative flourish, but a memento mori, a reminder of the danger that surrounded the medieval monarch.
In reality, despite it’s elabourate image, bryony is an unglamourous poisoner. The plant is the only gourd (family Cucurbitaceae) native to Britain, mostly found in Central and South Eastern England. Eating the plant produces powerful laxative effect, a scatological killer not fitting the intrigue of the royal court. There doesn’t seem to be any records of human poisoning by B. dioica, but it’s occurrence in hedgerows means livestock occasionally are poisoned by the root. Historical there would have been many more cases, however. B. dioica was used as a medicine, such as for leprosy, likely as a drug of last resort for an untreatable condition.
The B.dioica plant is remarkable for its large, rapidly-growing and foul-smelling root. Roots the size of one year old child were shown to John Gerard by the surgeon of Queen Elizabeth I, William Goderous.The size and speed at which the roots can grow means that they have been used by “knaves” to counterfeit the more alleged aphrodisiac mandrake (Mandragora officinarum). In his Universal Herbal of 1832, Thomas Green describes this practice; “The method which these knaves practiced was to open the earth round a young, thriving Bryony plant […] to fix a mould, such as is used by those who make plaster figures, close to the root, and then to fill in the earth about the root, leaving it to grow to the shape of the mould.” However, the notably effects of anticholinergic toxins of mandrake, inducing hallucinations and rapid heart rate, and the laxative bryony means these frauds were unlikely to have repeat customers.
The medieval margin illustrations feature identifiable bird species, but lack botanical detail. Bryonia dioica itself is a rapid climber of hedgerows. It’s five-lobed leaves have a rough feel with curling tendrils, white flowers and red berries which produce a foetid smelling juice when squeezed. The root is usually simple like a turnip and when cut produces a white foul smelling milk from the bitter succulent flesh.
Despite its surface charms, its scent, taste and effects are the exact opposite of belladona, meaning it lacks the glamour of this more famous poisoner.
With Valentine’s Day just around the corner, today’s post by Fang from the Visitor Team, is all about love! And for more about the objects and collections at Manchester Museum, have a look at the Curators’ blogs. All about love … Valentine’s Day is coming soon. In anticipation of a day all about love, I’ve taken a […]
For the past few months I’ve been working on a really exciting exhibition opening on the 20th of May: Object Lessons #MMObjectLessons Object Lessons celebrates the scientific model and illustration collection of George Loudon. Each of these finely crafted objects was created for the purpose of understanding the natural world through education, demonstration and display. […]
Guest Post by Laura Cooper
I remember hearing as a small child the rumour that swallowing a single apple seed would kill you. Whilst I later learnt that this was false, it is true that the cyanide in apple seeds means that theoretically, chewing a large number could cause poisoning.
Cyanide is a simple chemical produced by many organisms, often as an unwanted by-product. But cyanide is found in relatively high levels in many plant species, including the seeds of many common food plants, such as peaches, almonds, and legumes.
The cyanogenic plant I will focus on here is cassava, Manihot esculenta, also known as yucca. It’s tubers are a major carbohydrate source throughout the tropics due to its drought tolerance and ability to thrive in poor soil. It is probably most well known in the UK in the form of tapioca pearls in puddings.
Cyanide is a general defence against herbivores, as at the right dose it can kill anything that respires. There is variation in the levels of cyanide in fresh cassava tubers, “sweet” strains have as little as 20mg/kg whilst “bitter” strains have up to 1g/kg. It has been suggested that when early farmers selected plants with the best insect resistance, they were inadvertently choosing plants containing small amounts of cyanide. This means that sometimes the decision to grow (potentially) dangerous food is not a straightforward one, and higher cyanide cassava is often preferentially planted due their greater pest resistance and drought tolerance.
One of the founding principles of toxicology is an adage derived from Paracelsus: it is the dose that makes the poison. But the case of cyanide in cassava root goes to show that it is not only the dose that matters; the ability of the host to deal with the dose can be the difference between life and death.
The lethal dose of cyanide has been reported as 1mg of cyanide ions per kg of body weight, but it is difficult to ingest this from cassava. At lower levels, chronic cyanide poisoning can have serious effects, especially in people who are already malnourished. For those with diets low in Sulphur containing amino-acids, the body cannot add the Sulphur to cyanide to make it safe. They therefore struggle to remove cyanide at amounts a healthy person could do easily, so cyanide becomes cyanate, which is associated with neurodegenerative diseases. Severe cyanide poisoning can lead to a permanent paralysis of the limbs known as Konzo, which can be fatal. Unfortunately, the hardiness of cassava means it does become relied on when other crops fail and the population is already malnourished.
However, cyanide can be removed from cassava by proper processing. Cassava stores cyanide as a chemical called linamarin, which released cyanide when hydrolysed. This occurs which can occur in the gut if ingested, or when the cassava is soaked and mashed. If done thoroughly, processed cassava is safe to eat. However, if it is done by hand, the person preparing it can inhale a considerable quantity of cyanide gas. Additionally, the water by-products of cassava processing are rich in cyanide so can be an environmental hazard.
A genetically engineered strain of cassava lacking cyanide would be a valuable crop to large agricultural companies, as it would cut down on processing time. However, for small scale farmers with poor soil, drought and no pesticides, the cyanide in cassava acts as a built in pesticide and allows cassava to thrive when little else can. This shows perfectly that poisons are not always villains, but if dealt with carefully can be a vital part of a crops’ survival tool-kit.
For more information, see this excellent article on cyanide in food plants.
Guest post by Laura Cooper
Strychnine is an infamous poison. It is most well-known by its appearance in the novels of Agatha Christie as an effective but unsubtle method of murder. It was widely available in the 19th century from chemists as a rat poison, but this was taken advantage of by a number of real life serial killers including Dr Thomas Cream who gave disguised as a medicine and in alcohol. But strychnine had another side to it. Its caffeine- like stimulating effects means it has been used as a performance enhancing drug in competitive sports.
Strychnine, along with the toxin brucine, is present in the seeds of Strychnos nux-vomica. Though its name is lurid, it does not have anything to do with vomiting, “nux vomica” translates as ‘bumpy nut’. S. nux-vomica is in the family Loganiaceae and is native to South-East Asia and India. It is a medium-sized tree with large smooth oval leaves. The flowers have a repellent smell and the fruit is apple-sized with a hard shell that is orange when ripe. Inside, the seed are held in soft gelatinous pulp. The seeds are flattened disks covered with fine hairs, their flatness gives them the nickname ‘Quaker buttons’. The strychnine is concentrated in the seeds, but the wood also possesses poisons including brucine. Strychnine in the S. nux- vomica plays the same role as abrin in Abrus precatorius, it prevents herbivore species evolving which specialize in eating these seeds, as the poison is so general that it will likely kill any animal that eats the seed.
Strychnine poisons by blocking glycine from binding to specific neurons in the central nervous system. Strychnine prevents glycine from carrying out its inhibitory role, so causes the central nervous system to over-react to the smallest stimulus.
Initially the muscles become stiff, which is followed by hyperreflexia, where small stimulus trigger powerful reflex reactions. Later, increasingly frequent whole body convulsions occur. These resemble those in tetanus, an explanation often used to cover up strychnine poisoning. Eventually the respiratory muscles become paralysed and death by asphyxiation occurs usually within a few hours. Strychnine cannot cross the blood-brain barrier, so the victim is fully conscious throughout, making strychnine poisoning one of the worst ways to die I can imagine.
The main method of treating strychnine poisoning is crude. The patient is given barbiturates and muscle relaxants and removed from stimuli to prevent convulsions until the strychnine is metabolised by the liver which takes a few days.
However, S. nux-vomica extracts have been used in herbal and alternative medicine. It has been recommended for many different health issues from abdominal pain, heart disease and migraines though there is no evidence for its efficacy as a drug. However, a low dose of strychnine stimulates the central nervous system in a similar way to caffeine, but to a greater extent. This gives it great potential to act as a placebo, which is likely why it was reported to treat a wide range of illnesses, as well as to help spur athletes to victory.
S. nux-vomica‘s stimulating effects were used in 19th and early 20th century Europe and America in competitive sports as one of an arsenal of performance enhancing drugs, which were even deemed necessary for some endurance sports. Strychnine helped the American Thomas Hicks secure an Olympic Gold Medal. He was given strychnine and brandy during the 1904 Olympic marathon when he was flagging, though he collapsed after crossing the finishing line he later recovered. To this day, strychnine is on the list of banned stimulants in the World Anti-Doping Agency International Standard Prohibited List.
Guest blog by: Laura Cooper
Whilst many species of plants are referred to as mistletoe, the icon of Christmas is the European Mistletoe Viscum album. Mistletoe has a varied reputation; it is a symbol of Christmas and druidic ritual, a poisoner and a matchmaker.
The plant itself belongs to the Santalacea or sandalwood family. It is found throughout much of Europe, but in the UK is localized to the central south. V. album lacks its own trunk and instead grows in the crowns of host trees including apple, lime, hawthorn and poplar when its seeds are dispersed by birds smearing the sticky fruit and seed from their beaks onto the bark of the host. V. album is not a true parasite but a hemiparasite. This is because whilst the seedling sends its haustorium from the roots through the bark of the host to induce the host’s xylem vessels to supply it with water and nutrients, V. album makes its own sugars through photosynthesis. A heavy infestation of mistletoe can take over the entire crown of a tree preventing the host photosynthesising and building its own tissue which can lead to the death of the host.
V. album owes its toxicity to large amounts of the alkaloid tyramine throughout the plant, which is also present at lower levels in foods including cheese. As with most toxins, it is the dose that makes the poison, not the chemical. Whilst little research has been done on the effects of consuming V. album, it has been reported that consuming enough of the leaves or berries can result in nausea, abdominal pain, diarrhea and death. However, the well-known risks of mistletoe means poisoning cases are very rare. As the Poison Garden argues, artificial mistletoe is likely more dangerous as a choking hazard to children than live mistletoe is as a poison.
Whilst mistletoe is commonly linked with druids, the only account of a druid ceremony involving mistletoe comes from Pliny the Elder. He details a banquet and ritual sacrifice where a druid would climb an oak tree, cut the mistletoe with a golden sickle and drop it into a cloak to prevent it touching the ground and losing its power. The link between druids and mistletoe was picked up in the revival of druidry in the 18th century and today druids carry out a similar ceremony, without the human sacrifice! The tradition of kissing under the mistletoe at Christmas is not a Christian tradition but also derives from the association of mistletoe with fertility in druidic mythology. Christianity has a less favorable relationship with mistletoe, as according to tradition mistletoe wood was used to makes Christ’s cross and ever since could not grow upon the earth so was condemned to parasitic life.
Mistletoe has also been used as a medicine historically, including as an epilepsy treatment. Today, injection of extracts of mistletoe has been used as an anti-cancer treatment in alternative and complementary healthcare. Whilst it has been shown to kill cancer cells, the few trials done were inconclusive or poorly done, and the NHS advises that there is currently no reliable evidence that mistletoe is effective at treating cancer.
For more mistletoe information, see:
Guest blog by: Laura Cooper
Whilst volunteering at the herbarium I came across several small boxes containing bewitchingly bright red seeds and an equally garish TOXIC sign. They were labelled Abrus precatorius seeds, and that one of their common names is the rosary pea suggests that I am not the first to be taken in by their beauty. The seeds of Abrus precatorius have the eye-catching red of hawthorn berries capped with a black spot at the hilum, but glossy and sturdy enough to be drilled to make beads for jewellery.
The contrast between the beauty of the seeds and their toxicity inspired us to begin a blog series on toxic plants called The Poison Chronicles. We want to look at how they can kill, but also why they have evolved this ability and if the plant has any other products that are medicinally useful.
Abrus precatorius is a vine in the Legume family native to the Old World Tropics, but was introduced to the Neotropics for it’s ornamental value, but is now an invasive species. It proliferates after a forest fire so can out-compete slower growing plants, it’s suckering ability makes it difficult to remove.
But these seeds are more than just beautiful. They have earned their TOXIC label as they contain the toxin abrin, which has a very low fatal dose, reported in the literature as around 0.1 – 1μg/kg, making it one of the most toxic known plant products. Abrin acts by inhibiting protein synthesis, so can affect all cells in the body. A few hours after a person has ingested a lethal dose of abrin, they may experience severe vomiting, gastrointestinal bleeding, dehydration, multi-organ damage and death often within 36-72 hours. The incredible toxicity of abrin was occasionally used to secretly kill people in 19th century Bengal. The seeds were ground into a paste, shaping into a point known as a sui and left to harden in the sun. This was then mounted on a handle and stuck through the person’s skin by a surreptitious slap to the cheek.
Despite this toxic plant being widespread, there have been very few cases of abrin poisoning. The thick indigestible coat of mature seeds meaning that if seeds are swallowed whole, they are unlikely to release much abrin and symptoms are mild. Chewing the seed releases the toxin, and it has been reported that a single well chewed seed could kill. However, a case of a patient attempting suicide through ingesting 10 crushed A. precatorius seeds survived after swallowing activated charcoal. Except when used or taken deliberately, it is surprisingly difficult for humans to be poisoned by A. precatorius, so for most this plant poses more of a threat to your garden as an invasive than your health.
An obvious question is why these seeds contain such a deadly toxin. I have been unable to find any research on this. But it may be that the thick seed coat means the toxin isn’t a defence against herbivores ingesting the seeds at all. As it has been reported that the seed is dispersed by birds who would not chew the seed and would instead disperse them in faeces, it is possible it is a defence against mammals chewing the seeds.
A. precatorius has not always been seen as a deadly beauty, and has been used a traditional medicine. Extracts of the seeds have been used in the Pothohar region of Pakistan as a purgative and an aphrodisiac and in rural Bangladesh to treat erectile dysfunction. The symptoms of poisoning by abrin suggests very low doses could work as a purgative, there is a high risk of administering a lethally high dose.
A. precatorius‘ entire biochemical system makes it toxic, so single chemical plucked out of this network can have very different properties from the plant as a whole. In contrast its traditional uses, experiments have been done which show that abrin injected into laboratory mice damages the DNA and reduces production of sperm cells, though the long time period needed for DNA repair to occur means it is unlikely to be used in commercial birth control.
Abrus precatorius demonstrates the multi-faceted nature of plants: at once a beauty and a (potential) killer; a toxin and used as a medicine.
We hope you have enjoyed our first installment of The Poison Chronicles. You can find more information following the link below
What wondrously poisonous plant would like to find out about next? Leave your comments below.