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Plants Dangerous to Humans
People in the Middle East once believed the existence of a man-eating tree. In 1878, an article written by Carl Liche, a German explorer, attained widespread attention. He explored the dark regions of Madagascar, assisted by a group of Mkodo tribesmen. In his texts, Carl mentions that he was a witness to a rather unusual scene. A woman from the Mkodo group drank the nectar from a weird-looking tree and, sensing a presence, the pineapple-looking tree wrapped her in its branches and "ate her up."
The pineapple-looking tree might have been an exaggeration of the pitcher plant, which exists in hot and humid regions. The pitcher plant attracts insects and vermin to it. Once they fall into the pitcher, they are unable to escape and become food for the plant.
Although human beings don't need to be afraid of any such danger, these deadly and beautiful creatures certainly attract everyone's attention. Even though no man-eating tree exists in today's world, deadly plants do exist. Following is a brief compilation of some of the most dangerous plants that grow today.
Top 10 Most Dangerous and Poisonous Plants
- Nerium Oleander
- Cicuta or Water Hemlock
- Abrus Precatorius or Rosary Pea
- Atropa Belladonna or Deadly Nightshade
- Castor Oil Plant
- Taxus Baccata or the English Yew
- Ageratina Altissima or White Snakeroot
- Aconitum or Aconite
- Datura Stramonium aka Jimsonweed
- Hippomane Mancinella or Machineel
1. Nerium Oleander
Probably the most poisonous plant on Earth, every part of this plant is full of toxins. Two of the most powerful ones are oleandrin and neriine. An oleander's poison is so strong, in fact, that it can poison a person who simply eats the honey made by bees that have digested oleander nectar.
Despite its deadly nature, it is planted for decorative purposes. The oleander produces a lovely fragrance; however, the animals stay away. They are often used for highway barriers. Its rapid growth is used to prevent erosion at new construction sites.
Oleander is poisonous to most animals as well as humans. Ingestion of oleander leaves has caused deaths in human beings. Though the toxin remains deadly for approximately the first 24 hours after ingestion, the odds of survival increase dramatically if the patient survives for a few hours. For successful treatment, the patient is induced to vomit, their stomach may be pumped, or they may be fed activated charcoal to absorb as much of the poison as possible.
2. Cicuta or Water Hemlock
Found mainly in the marshy areas of the American continent, this plant contains a deadly toxin, cicutoxin, which is concentrated mainly in the roots. Unfortunately, the white roots of the plant are often mistaken for the parsnip. Over the decades, it has earned itself a reputation of one of the deadliest plants on the planet.
Cicutoxin causes violent and painful convulsions, nausea, vomiting, cramps, and muscle tremors. Those who survive the poisoning experience long-term health conditions, such as amnesia. No amount of water hemlock root is considered safe to ingest.
Livestock have long been affected, leading to the common name "cowbane." Poisoning in livestock is common and typically occurs following ingestion of roots of the plant. In the spring when the ground is soft, grazing animals tend to pull the entire plant out of the ground, ingesting both the foliage and the roots. Roots exposed by ploughing can also be the source of livestock poisonings. Ingestion of plant material may cause death in the animal in as little as 15 minutes.
3. Abrus Precatorius or Rosary Pea
Possessing beautiful fruits, the rosary pea contains black and red seeds. Used extensively in making imported jewelry, they are popular as rosary prayer beads.
The pea seeds contain the poison abrin. The seeds are completely safe until they are scratched or the outer coating is damaged. Due to obvious reasons, it poses a greater danger to the jewelry maker than to the wearer. These are aggressively growing creepers which can cover a whole region if not kept in check.
Abrin, the rosary pea poison is much more poisonous than ricin. About 2.5 milligrams of abrin is enough to kill a human, and each pea possesses more poison than the above-mentioned amount. It inhibits protein synthesis by bonding with the cell membranes.
Symptoms of rosary pea inhalation poisoning are difficult breathing, fever, nausea, and fluid in the lungs. If ingested—and the seed coating is broken—rosary pea seeds cause severe nausea and vomiting, which eventually leads to dehydration and ends with the kidneys, liver, and spleen shutting down. Death usually follows within three to four days.
4. Atropa Belladonna or Deadly Nightshade
Probably the plant with the scariest name, the deadly nightshade grows to a height of 1.5 meters and can be recognized by the dull, dark green leaves, and bell-shaped purple flowers.
The sweet and juicy fruits make them tempting for children. Though it is found sparsely in the wild regions, it is limited to cultivation. It's one of the very few plants which are deadly for human beings but completely safe for animals and birds.
The deadly poison attacks the nervous system, rendering the nerve endings in involuntary muscle paralysis. Symptoms include dilated pupils, sensitivity to light, blurred vision, headaches, confusion, and convulsions. As few as two ingested berries can kill a child, and 10 to 20 berries would kill an adult. Even handling the plant can cause irritation.
In 2009, poison control centers across the United States handled 58,687 cases regarding plant poisonings [source: AAPCC].
5. Castor Oil Plant
Castor plant originated in Africa and is now found worldwide. It bears yellowish green flowers with a red center. The leaves are large with toothed edges. In ancient times, the castor bean was used in ointments, and allegedly, Cleopatra applied the oil to the whites of her eyes to brighten them.
You must have heard about castor oil, a mild-tasting vegetable oil used as a food additive, flavoring in candy production, laxative, and to induce labor. It is derived from the plant seeds, which are 40-50% oil.
This plant contains the deadly toxin: ricin. Ricin is found in high concentrations in the seed coating. Though seed poisonings are rare, there have been fatalities.
Symptoms of castor poisoning include nausea, abdominal cramps, vomiting, internal bleeding, and kidney and circulation failure. Many people suffer from an allergic reaction to the dust from the seeds and may experience coughing, muscle aches, and difficulty breathing. Exposure to the dust is most common in areas where the beans are processed for commercial use.
6. Taxus Baccata or the English Yew
Given the abundance in church graveyards across Great Britain, no doubt the English yew stands a deserving candidate in the list. These plants are believed to have played a part in pagan spiritual practices. Today, they are a symbol of the immortality of the soul.
These giant trees stand as tall as 22 meters. All parts except the bark are poisonous. Consumption of the leaves, and to a lesser extent the seeds, can lead to increasingly serious symptoms, including dizziness, dry mouth, dilation of the pupils, weakness, irregular heart rhythm, and possibly death.
The yew has been used for productive purposes as well. It served as a good material for making bows. It possesses medicinal qualities, such as a treatment of water elf disease. Studies show its enormous potential as an anti-tumor. Yew extract is used for Taxol, which slows the growth of numerous cancers.
7. Ageratina Altissima ot White Snakeroot
Credited with killing Abraham Lincoln's mother, the white snakeroot is a shade loving weed which grows in the eastern and southern United State and contains high levels of trementol, a dangerous toxin. European Americans traced the cause of Abraham Lincoln's mother's death to snakeroot, although today Dr. Anna Pierce Hobbs Bixby is credited with identifying the plant in the 1830s. Legend has it that she was taught about the plant's properties by a Shawnee woman whose name is lost to history, but she and her people would have had deep knowledge of the herbs and plants in the area. It has bunches of flowers at the end of its branches.
It causes milk sickness, a condition that affects people consuming milk from the cow who consumed the plant. The plants are also poisonous to horses, goats, and sheep. Signs of poisoning in these animals include depression and lethargy, placement of hind feet close together (horses, goats, cattle) or far apart (sheep), nasal discharge, excessive salivation, arched body posture, and rapid or difficult breathing.
In humans, symptoms include bad breath, loss of appetite, listlessness, weakness, vague pains, muscle stiffness, vomiting, abdominal discomfort, severe constipation, coma, and possibly death.
8. Aconitum or Aconite
One of the most beautiful poisonous plants, aconite, contains blue, white, or flesh-colored bunches of flowers at the top of the stalks. Though the plant looks very beautiful, every part of it is laced with poison and is known to poison gardeners and backpackers who mistake its white carrot-like root for horseradish or some other herb.
Contact with the plant can cause tingling, numbness, and in many cases, heart problems. Consumption can lead to a burning sensation in the mouth followed by increased salivation, vomiting, diarrhea, a tingling sensation in the skin, changes in blood pressure, heartbeat irregularities, coma, and sometimes even death.
The past has witnessed the use of Aconite for shedding blood. Nazis use the poison to lace their bullets. Ancient Greek shepherds laced darts with aconite to kill wolves and protect their herd. The Harry Potter series shows Severus Snape using aconite to convert Remus Lupin into a werewolf.
9. Datura Stramonium aka Jimsonweed
With its pointed fruits and leaves, jimsonweed has truly created a scary image for itself. The plant has been long related to spiritual and voodoo properties due to its hallucinogenic properties. Believed to have originated from the Americas, it's found all around the world now and has known medicinal properties such as relieving asthma symptoms and as an analgesic during surgery or bone-setting.
However, its alkaloids which are responsible for the hallucinogenic and medicinal properties are fatally toxic and even a slightly higher dosage can result in hospitalization and death. Even the nectar and petals of its beautiful white or lavender trumpet-shaped flower are dangerous. They, like the rest of the plant, are tainted with the toxins atropine and scopolamine.
10. Hippomane Mancinella or Machineel
Manchineel derives its name from manzanilla (little apple) due to the resemblance of its fruit and leaves to that of an apple. Its present-day Spanish name is in fact manzanilla de la muerte, "little apple of death." Found throughout the Florida Everglades, Central America, and the Caribbean, these trees are known to cause harm even without contact with the body. Break a twig, and the dripping white sap can cause damage, including rashes, skin irritation, coughing, loss of voice, etc. The dripping sap from these plants can even damaged car paint.
These apple-like fruits, if ingested, can cause blisters in the mouth, swell the throat to shut it off, and even cause gastrointestinal problems. These trees are known to grow near beaches, and thousands of tourists face the wrath of this tree every year. So, if you're heading to these regions, try to keep on guard for this deceptive plant.
Protecting Yourself From Poisonous Plants
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
Alpha Skua on May 31, 2020:
The rule of thumb should be do not eat any strange fruit or plants you don't know about the same rule should apply to Mushrooms in the wild
dave on April 18, 2020:
what about the dolls eyes plant
Caden on January 23, 2020:
Thanks for making this, really helpful!
Ben Hergenrother on May 07, 2019:
This was really helpful Because I have some of these plants near my house thank you.
sana on February 11, 2019:
Anianimation Tang YT on October 02, 2018:
This helped me with my school assignment thanks
THEBOI GAMER on yt on August 20, 2018:
thanks this helped me in my school project and can you plz subscribe to my youtube channel its THEBOI GAMER plz ladies and gentlemen
Joselyn on June 04, 2018:
This helped with a project so i can help kids in my school be safe!! :D
Belinda the plant pro on May 31, 2018:
Wow...this site is amazing. I learnt sooooooo much and my favourite poisonous plant is the Nettle family and the Milky Mangrove;)) if you know what i mean;))) Obivion Rose: i know what you're saying, i too wish i could test on people....
Oblivion Rose on December 17, 2016:
I like poisonous plants I like studying them and some of their effects but I don't think I can use it on a real person or animal
Cat on February 25, 2016:
In the Nightshade part, That's Solanum Dulcamara; Aka Bittersweet nightshade or Climbing nightshade.
Chinmay Das (author) from Mumbai, India on February 20, 2014:
It's definitely possible.
A few of the plants discussed above are not only known to possess harmful toxins, but have shown their life threatening capabilities on numerous occasions.
A word of caution is always advised while handling these beautiful, yet dangerous creatures.
Chinmay Das (author) from Mumbai, India on February 16, 2014:
We often hear numerous instances of people/animals being poisoned by such plants. This wouldn't be possible if these plant's weren't so beautiful.
Dianna Mendez on February 16, 2014:
This is very interesting and useful for those who live near wooded areas. Some of the plants are so pretty and I can see how one would be tempted to think the fruit is edible.