Poisonous Plants

Yesterday’s meeting was all about plants that are irritants and plants that are poisonous. There are so many poisonous plants, only a handful are discussed below.  I’ve started with the most common poisonous plant family.  

 
Solanaceae  - Potato  Family

The most well known plants in this family are potatoes, tomatoes, peppers, aubergines, chillies, pepinos and cape gooseberries, but it includes some wild flowers and ornamental shrubs.

In general, in the Solanaceae family the green parts and unripe fruit are poisonous to humans, not necessarily to animals.

Symptoms occur 6-12 hours after ingestion, fever, sweating, vomiting, abdominal pain, diarrhoea, confusion and drowsiness.  Children have died from eating the unripe berries.

Solanum tuberosum - Potatoes - were introduced into Europe in the 16^th century by the Spanish.  It took a while to become the staple it is today.  Initially people did not know what part of the plant to eat.  Mistakes were made, some ate the stems and leaves.  The stems, leaves and the green on a potato are poisonous, they contain 'solanine' a glycoalkaloid that could cause death after a period of weakness and confusion, followed by a coma.  With better information the popularity of potatoes increased.  Nowadays potato poisoning is a rare occurrence.  If it occurs, it is by eating green potatoes or drinking potato leaf tea. 

Tomatoes – the leaves and stem of the tomato contain 'solanine' the same as in potato.

Solanum nigrum - Black Nightshade –Morelle noire -Zwarte Nachtschade

A common weed.  The black berries contain 'solanine' again the same active ingredient as in potato. This plant is sometimes confused with Atropa belladonna as both have black berries.  Solanum nigrum berries grow in bunches, Atropa belladonna berries are solitary.

Solanum dulcamara - Bittersweet  - Douce-amère - Bitterzoet

Bittersweet is a climber, has purple flowers and bright red berries.  Same alkaloids as in potatoes and as in Black Nightshade.  Again poisoning is mostly by ingesting berries.   The name comes from the taste, it tastes first bitter and then sweet.  Children have died from eating Bittersweet, but not many as the initial taste puts them off.

The next  4 mentioned plants, Atrope belladonna, Hyoscyamus niger, Mandragora autumnal is and Datura stramonium all contain in more or lesser degree the active ingredients, 'hyoscyamine, scopolamine and atropine'.  Dature stramonium being the most potent.

 
Atropa belladonna  - Belladonna or Deadly Nightshade – Belladone - Wolfskers

A plant still used today.  Its main active ingredient is ‘atropine’ used by eye specialists to dilate the pupils and to temporarily paralyse the muscles that help the eyes to focus.  The leaves and roots have sedative and calming properties.  First they stimulate the central nervous system, then they suppress it.  Used as well for breathing problems, rheumatism, muscle ache and stomach cramps.

Hyoscyamus niger – Henbane – La jusquiame noire –Bilzekruid

Henbane acts calming, as a painkiller and against cramps. The smell is enough to cause giddiness and stupor.

Mandragora autumnalis – Mandrake – La mandragore – Alruin

 

It was once used in magical and orgiastic rituals.  Tea made from the roots or leaves causes first excitement then numbness, hence being used in magical and orgiastic rituals.  In Homeopathy it is used for astma and cough. 

Datura stramonium – Datura – Doornappel. 

Even picking the leaves can cause symptoms in certain people.  Picking leaves was done commercially for the pharmaceutical industry in the first half of the 20^th century.  It was used to relieve spasms of the bronchioles during astma.  Some of the pickers experienced impaired vision followed by eye infection. 

All these 4 above mentioned plants contain hallucinogenic compounds.  By smearing the ointment on certain places, under the armpits or on the vagina, the hallucinogenic effect worked fast, much faster than ingesting it, and in addition it would avoid intestinal discomfort and the effect was stronger as it was not partially broken down by the liver. The idea they were flying on a broomstick comes from using these drugs.

Sambucus nigrum – Elderberry - Sureau - Vlierbes

The flowers and berries are edible, but the roots and the leaves are poisonous and will cause severe stomach problems.

Ricinus communis – Castor Oil Plant - Ricin - Wonderboom

It belongs to the Euphorbia family.  The seeds (40-60% oil) produce the castor oil.  Castor oil was widely used as motor oil, now mostly replaced by synthetic oils.  Internally it was used for constipation.

The plant is considered one of the most poisonous plant in the world, 4-8 seeds is enough to kill an adult.  It is not a poison that is used in suicides because of painful and unpleasant symptoms – it causes nausea, severe vomiting, convulsions and then disintegration of kidneys, liver and spleen. These symptoms can take up to a week.

The principal poison in the castor oil plant is called ‘ricin’.   The workers who collect the seeds work by strict safety guidelines to prevent accidental death.  

Castor oil seeds are easy to procure, and in the form of purified ‘ricin’ could be used as a terrorist weapon, e.g. added to food and beverages. It is not destroyed by heat, and potentially could be added to an explosive device. 

The political assassination in London of Georgi Markov, a broadcaster and journalist for BBC World Service was carried out by using the tip of an umbrella.  A micro-engineered pellet containing ricin was fired into Markov’s leg.  It took 4 days before he died of gastroenteritis and organ failure.

The greatest concerns are that the symptoms are misdiagnosed.

Commercially bought cold pressed castor oil is not toxic, internally or externally.

Cyanide

Cyanide is a quick acting poison.  Zyklon B (brand name), a gas with as its main component  ‘hydrogen cyanide’ HCN (prussic acid – acide prussic - blauwzuur) was used in the death camps during World War II.  Ironically it was developed by Fritz Haber, a German Jew.  

Stories abound of spies or criminals, biting into cyanide tablets and dying very quickly.  During fires, burning plastic and polystyrene foam give off cyanide gases.

Hydrogen cyanide is synthesized through a variety of chemical processes.  It is used in industry in explosives, engraving and dyeing processes and was used in vermin and insect poison. 

The effect of poisoning by Hydrogen cyanide restricts oxygen intake and causes suffocation.

Lots of plants contain hydrogen cyanide (prussic acid) in smaller or larger doses.

Prunus amygdalis var. amara - Bitter Almond 

There are two types of almonds, sweet almonds and bitter almonds.  Bitter almonds, because of their flavour are used for culinary purposes. Unfortunately raw nuts contain ‘prussic acid’.  Before consumption, bitter almonds must be processed to remove the poison.  Heat destroys the poison.

Cherries – Cherries belong to the same family as plums, apricot and peaches.  All these fruits contain poisonous compounds in their leaves and seeds.  Almonds are a member of the same family but they are the only fruit that is harvested for their seeds rather than their fruit.  When the seeds of the cherry are crushed, chewed, or even slightly injured, they produce 'prussic acid (hydrogen cyanide)'.

Apples – Like the almonds and the cherries, apples contain prussic acid, but in much smaller doses.  Apple seeds are very often eaten by accident, but you would have to chew quite a few to have any symptoms.

Exposure to low levels of cyanide over long periods, e.g. after use of Cassava roots as a primary food source as is done in tropical Africa, results in weakness, paralysis and mild liver and kidney damage.

Rhubarb – Rhubarbe - Rabarber

The leaves are poisonous, in addition to the poison they contain a corrosive acid.  The stems are edible and the roots have been used for centuries as a laxative.

Aconitum napellus – Monkshood – Aconit napel - Monnikskap

Another very poisonous plant.  All parts are poisonous, but the roots contain the most poison. 

Spears and arrows were coated with the poison and in Roman times it was used to eliminate criminals and enemies.  Later it was banned and if anyone was discovered growing Aconitum, they were sentenced to death. 

It works on the cardiovascular and central nervous system.  It reduces fever, has painkilling and calming properties.  Once used internally now only externally for rheumatism, neuralgia and sciatica or in homeopathic medicine. 

Care should be taken by wearing gloves when handling the plant.  Aconite poisoning has been described as: “Burning of mouth, constriction and pain in throat and chest, greatly laboured breathing, vertigo, diminished vision or blindness, slight convulsive twitching and a sense of impending doom. It leaves no traces.

Digitalis purpurea – Foxglove – Digitale pourpre - Vingerhoedskruid

Digitalis lanata – Woolly Foxglove – Digitale laineux - Wollig Vingherhoedskruid

Digitalis lutea – Yellow Foxglove – Digitale à petites fleurs -Geel Vingerhoedskruid

It was William Withering who discovered the uses of Foxglove to treat dropsy (oedema).  He published his findings in 1768.  He was a young country doctor who in his capacity as doctor visited a young women who was bedridden.  This lady, as a hobby, painted plants and flowers.  He was attracted to her and to please her, as she was unable to leave the bed, he would collect wild plants for her.  He became interested in the plants he collected and the more he learned about them, the more he realised the possible medical potential of some plants.  He was particularly interested in the Foxglove.  He read all the papers available on Foxglove and decided it needed further examining.  He married the young lady and set up a practice in Bristol.  At the same time he opened a clinic for the poor, so he had ample patients to try out his experiments. He decided to use the leaves when the plant was in flower just before setting seed, before or after would give different levels of active ingredients.  It turned out to be an effective medicine to treat dropsy (fluid retention in the connective tissue of the body) often caused by heart problems.

During William Withering’s days Digitalis purpurea was used, the active ingredient 'digitoxin' was effective but the toxin accumulated in the liver. 

Today, Digitalis lanata is used.  The active ingredient is different from D. purpurea, is called 'Digoxin'  It is  used to treat several heart conditions.  It increases the contractions of the heart without using more oxygen, and regulates the heartbeat.  Digitalis lanata works 4 x stronger than Digitalis purpurea.

Fatal accidents have occurred but are rare, i.e. children drinking from a vase with Digitalis flowers or if it is confused with Symphytum officinale (Comfrey – Consoude - Smeerwortel).

Conium maculatum – Poison Hemlock – Ciguë tachetée - Gevlekte Scheerling

Hemlock was used by the ancient Greek State as a death sentence. The accused had to drink a cup of Hemlock. 

It was the poison given to the philosopher ‘Socrates’.  How poisonous it is varies greatly, it is supposed to be far more poisonous in hot Mediterranean climates than in northern climates, but should always be treated with caution. 

It belongs to the Carrot family (Umbelliferae) and as such looks quite similar to many of the other plants in the family.  Nature’s way of warning you that something is wrong is its foetid, unpleasant smell and a very sharp taste.  The stem is hollow and covered in brownish-red spots.

Deaths have occurred by incorrectly identifying the plant and mixing it up with other Umbelliferea. 

It is a biennial and in its first year looks remarkably like parsley.  The seeds are the most poisonous part.  It attacks the peripheral nervous system. Formerly used in epilepsy, mania, cramp and astma. 

In excess – difficulty in breathing, paralysis, stupor and finally death. 

Plato describes Socrates’s death as:  "a slow ascending paralysis, beginning in Socates’ feet and creeping steadily up his legs towards his chest, with Socrates’ mind remaining clear until the end.  Death arrives calmly and peacefully"  unquote.  (Journal of the International Plato Society).

Taxus baccata – Yew – If - Taxus of Venijnboom

All parts of the shrub/tree are poisonous, except for the fruit when the pip has been taken out.  It contains a chemical ‘taxotere’, which is used in the treatment of breast, ovarian and prostate cancer.  Taxus clippings are collected in several countries, as part of the process of making ‘taxotere’. Taxotere interferes with cell division.

Nerium oleander – Oleander

A very common plant in our area, deaths occur if the wood is used for cooking purposes and dogs biting into the branches.

Some of Wellington’s men in the Peninsular War of 1807-14 are said to have died after eating meat cooked on skewers made from oleander.  It contains cardiac glycosides, the poison attacks the stomach, heart and central nervous system causing  drowsiness, tremors, seizures, collapse, coma that can lead to death. 

The sap if in contact with the skin can cause blistering, irritation and soreness, but nothing else. 

Never burn oleander branches, inhalation of burning oleander can cause in varying degree the symptoms of oleander poisoning.

Some poisonous plants originating from outside Europe

Strychnos nux-vomica and Strychnos ignatii

One of the most well known poisons must be ‘strychnine’.  There are 196 species of trees and climbers in Asia, America and Africa that have the component ‘strychnine’ in their seeds or bark.

In general ‘strychnine’ comes from the Strychnos nux-vomica tree from Asia.  A 12 m tall tree with orange fruits the size of apples, each fruit contains 5 seeds.  The other tree is Strychnos ignatii  from the Philippines and China. 

'Strychnine' can be absorbed through ingestion, inhalation or by injection and is very quickly absorbed.  50% of ingested ‘strychnine’ is absorbed and entered into the tissues in 5 minutes.  60-100 mg ‘strychnine’ is fatal, 1-2 hours.  It produces one of the most dramatic and painful symptoms of toxic reaction. 

In small quantities it has been used as a performance enhancing drug.  It was used by athletes before testing came along. 

In the 1992 Barcelona Olympics a Chinese volleyball player was taking as a tonic, capsules that contained 'strychnine'.  She was not aware what was in these capsules.  Although she was banned, no blame was attached to her. 

Apart from  enhancing qualities it was mostly used to kill vermin.  As it is quite indiscriminate, it could quite easily kill a cat or dog.   It has now been banned to be used as a pesticide in several countries.

Curare

Curare is a general name for arrow poison used by the native population of Central and South America to kill prey.  The poison is derived from different trees and climbers but principally from the Chondrodendron tomentosum climber.

It produces a weakness in the skeletal muscles, and in high enough doses, death by asphyxiation due to paralysis of the diaphragm. 

It’s muscle relaxing properties were used from 1930’s during surgery.  Nowadays it has been replaced by synthetic drugs as the dosage is easier to establish. 

It is  harmless if taken internally as the compounds of the drug are to large to pass through the lining of the digestive tract to be absorbed into the bloodstream.  For the same reason the natives are able to eat the meat caught with the poisoned arrow.

Catharanthus roseus – Rose Periwinkle – La pervenche de Madagascar – Roze Maagdenpalm

From the Rose Periwinkle the alkaloid ‘vincristine’ is extracted.  It is used in treatment of several cancers, specifically in the treatment of childhood leukaemia and has contributed to the survival rate increase from less than 10% in 1960’s to 90% today.

See Mavis’s article on Irritants.  
For further reading access the poisonous plants website : thepoisongarden.co.uk
also, the poison garden at Alnwick Castle

Bibliography :  Wikipedia; Encyclopedia of Herbs and their Uses - Deni Bown; Herbs and Herbalism - Malcolm Stuart
Photos:  Web