By Alastair Culham This is the 100th #AdventBotany blog and the fourth for Christmas day. The first Christmas blog featured the Star of Bethlehem, the second, Christmas Cactus, and the third, a tough and Christmas flowering heather. This is the first Christmas blog to feature an edible plant. This blog is a brief introduction to…
#AdventBotany Day 24: Juniperus communis – the most delicious of the Cupressaceae By Meg Cathcart-James
By Meg Cathcart-James Juniperus communis with cones Juniperus communis is the most widespread of the juniper species. Juniperus is within the conifer family Cupressaceae. Whether as a small evergreen tree or a shrub, it is one of the most globally widespread woody plants. J. communis is cultivated in the horticulture trade as an ornamental, with…
By Maria Christodoulou & Kalman Konyves With Christmas approaching quickly, many of you are braving the cold and crowds to complete your Christmas shopping. If you do have time for a break you may enjoy one of the most popular lattes on the high street, a Chai latte. Before we go off at a tangent…
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Most curators have those niggling objects at the back of their stores. Models and illustrations previously used for teaching or display in the dim and distant past, but kept for a rainy day. Not quite real objects and not the kind of thing you would necessarily want to accession.
Well, we’ve embraced these wonderful objects in our new exhibition: Object Lessons.
Brendel Models, George Loudon Collection
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.
The object-rich exhibition will look at this incredible collection through themes such as Craftsmanship, the Teaching Museum and the Microscopic.
Here’s a selection of some of my favorites in the exhibition:
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Guest Post by Laura Cooper
For much of human history, people have sought to find a way to prove or disprove a person’s guilt. Today, we hope evidence and a fair trial will do this, but people have always wanted a quick and definitive way of doing this. This is where the idea of the trial by ordeal came in. Most people are familiar with the practice of dunking suspected witches in bodies of water in parts of 17th century Europe; if they floated they were guilty and if they sunk they were innocent. But in what was then called the Calabar region (now North-East Nigeria) in the 19th century, a particularly poisonous seed was used in these trials by ordeal. This plant, known as the Calabar bean, Physostigma venenosum, became notorious as a poison. However, the principle lethal chemical of the Calabar bean, phystostigmine, was investigated by a number of physicians in Europe as an antidote to poisoning by atropine. Though both compounds can kill, their methods of murder are mirror images of each other, so that one can be used to cancel out the effects of the other; and so a poison can become a cure.
I can only find reports of the use of P. venenosum in ordeals in reports by Europeans visiting Calabar in 1846, who reported that 120 people died annually in the region by the Calabar bean. A person suspected of a misdeed would be made to consume the bean, likely soaked and crushed to release the toxins rather than whole. If they were guilty they would die, if they were innocent they would survive. It has been reported that swallowing the bean probably won’t result in death, but consuming a crushed seed would release toxins, like Abrus precatorius. Consuming enough seeds can lead to increased salivation, seizures, loss of control of urination and defectation and death by asphyxiation. Physostigmine has an oral LD50 (a dose which will kill half of a large group of mice) of 4.5 mg/kg, and the maximum number of beans reported eaten and survived is 35. Depending on a person’s weight and health, it is possible that one person may survive and another die after being given the same number of beans, and this difference can be attributed to their guilt or innocence.
The bean extract was known by medics in Europe, and extracts were used to constrict the pupil by ophthalmologists. Aware of it’s effects, in 1864 the Prague ophthalmologist Niemetschek suggested that a patient with atropine poisioning be given Calabar bean. Thomas Fraser investigated the effects of P. venenosum extract rigorously, and identified the chemical phystostigmine as the active chemical.
Phystostigmine acts as an acetylcholinesterase inhibitor. This means it prevents the neurotransmitter acetylcholine from being broken down, so the parasympathetic nervous system is continually stimulated. This is the exact opposite effects of atropine, an anticholinergic drug derived from Atropa belladonna, which I have written about before. Atropine causes anticholinergic syndrome, making the patient “dry as a bone, blind as a bat, red as a beet, mad as a hatter, hot as a hare”, as medical students remember it.
But many other chemicals and conditions can cause anticholinergic syndrome, and despite many published cases of phystostigmine being used to treat anticholinergic syndrome safely and effectively, it has been reported as being underused. It could be speculated that this underuse could be due to the gruesome reputation of the source of the chemical, the Calabar bean, and therefore a hesitancy to recommend the drug. But whilst the drug is dangerous at a high enough dose, the ordeals themselves show that it is survivable (if you are innocent, that is!). We return again to the common theme of plant poisons; everything has a lethal dose, even water, what is more interesting is what doses lower than this can do to the human body.
Guest Post by Laura Cooper
Binomials can be a pain to learn, but they often have a hidden poetry. Deadly nightshade’s common name stresses its notoriety as a poison. But it’s binomial, Atropa belladonna, is far more beautiful and apt. The genus name is derived from Atropus, one of the three Fates of Greek Mythology, whose shears could cut the threads of life. The species name belladonna is the Italian for beautiful woman, named so because of the plant’s use in giving pleasingly dilated pupils. A figurative translation of the name could be femme fatale, appropriate for a plant whose main danger to humans is to the forager lured to pick and eat the glossy black berries.
The Herbarium has a large model of these berries displayed on a cabinet in the main room. It caught my eye as I was returning the gloves I wore to find Atropa belladonna Herbarium sheets. Compared to the shriveled fruits I had just seen, this was a regal fruit with the sepals like a ruff and a grandly arching stem. A belladonna indeed.
Atropa belladonna is one of the most common plants involved in poisoning throughout most of Europe and central Asia, but is still no minor threat. For example, the plant topped the list of plants causing severe poisoning in Switzerland between 1966-1994. Of a total of 24,950 cases of contact with poisonous plants, 135 cases (0.6% of total) were serious poisonings with sufficient information. Atropa belladonna was involved in 42 of these cases, but no deaths were reported. This doesn’t mean the plant should be treated lightly though. It has the potential to be quite dangerous.
As with many poisonous plants, it is very difficult to get an accurate measure of the lethal dose. Some report that an adult would be killed by 10-20 berries, whilst others report a case of children who had eaten eaten up to 40 berries and survived after hospitalisation.
A. belladonna‘s deadly potential is principally derived from three toxins, the tropane alkaloids hyoscine, hyoscyamine and atropine. The toxins have an anticholinergic effect, which means they affect neurones by competing with the neurotransmitter acetylcholine for muscarinic receptors. After a delay, this leads to an inhibition of the parasympathetic nervous system. This produces anticholingeric syndrome, whose symptoms are remembered by the mnemonic, “dry as a bone, blind as a bat, red as a beet, mad as a hatter, hot as a hare”. If the dose is high, this can lead to psychosis, convulsions, respiratory failure and death.
A. belladonna and its derivatives were favoured tool for the poisoner. In the late 19th century, the psychopathic American nurse Jane Toppan used atropine in concert with morphine to kill over 31 people. As atropine and morphine produce opposite responses, atropine “speeds up” the system whilst morphine slows down the body, Toppan balanced the doses of both drugs to prolong her victims’ struggle until a fatal dose was given.
However, atropine in the right hands can be a very useful chemical, even a lifesaver. It is the standard antidote for nerve gas poisoning, as it blocks the excess acetylcholine the nerve gas produced. It is also used to dilate eyes for examination by an ophthalmologist and is given to patients after cardiac arrest. Ironically, the very “poison” that Jane Toppan used to kill a victim whose death was originally recorded as heart disease is now used to help save patients from dying from a heart attack. There can always be a useful side to the proverbially deadliest of plants.