Poisonous Plants

Source:  Poisonous Plants    Tag:  symptoms of poison sumac

Apple Seeds
Apple ( Malus domestica). Seeds are mildly poisonous, containing a small amount of amygdalin, a cyanogenic glycoside. The quantity contained is usually not enough to be dangerous to humans, but it is possible to ingest enough seeds to provide a fatal dose.

Cherry ( Prunus cerasus), as well as other  Prunus species such as peach ( Prunus persica), plum ( Prunus domestica), almond ( Prunus dulcis), and apricot ( Prunus armeniaca). Leaves and seeds contain cyanogenic glycosides.

Kidney Bean Plant
Kidney bean or  common bean ( Phaseolus vulgaris). The toxic compound phytohaemagglutinin, a lectin, is present in many varieties of common bean but is especially concentrated in red kidney beans. The lectin has a number of effects on cell metabolism; it induces mitosis, and affects the cell membrane in regard to transport and permeability to proteins. It agglutinates most mammalian red blood cell types. The primary symptoms of phytohaemagglutinin poisoning are nausea, vomiting, and diarrhea. Onset is from 1 to 3 hours after consumption of improperly prepared beans, and symptoms typically resolve within a few hours. Consumption of as few as four or five raw kidney beans may be sufficient to trigger symptoms. Phytohaemagglutinin can be deactivated by cooking beans at 100 °C (212 °F) for ten minutes. However, for dry beans the U.S. Food and Drug Administration (FDA) also recommends an initial soak of at least 5 hours in water; the soaking water should be discarded. The ten minutes at 100 °C (212 °F) is required to degrade the toxin, and is much shorter than the hours required to fully cook the beans themselves. However, lower cooking temperatures may have the paradoxical effect of potentiating the toxic effect of haemagglutinin. Beans cooked at 80 °C (176 °F) are reported to be up five times as toxic as raw beans. Outbreaks of poisoning have been associated with the use of slow cookers, the low cooking temperatures of which may be unable to degrade the toxin.

Nutmeg Plant
Nutmeg ( Myristica  fragrans). Contains myristicin. Myristicin is a naturally occurring insecticide and acaricide with possible neurotoxic effects on neuroblastoma cells. It has psychoactive properties at doses much higher than used in cooking. Raw nutmeg produces ant cholinergic-like symptoms, attributed to myristicin and elemicin. The intoxicating effects of myristicin can lead to a physical state somewhere between waking and dreaming; euphoria is reported and nausea is often experienced. Users also report bloodshot eyes and memory disturbances. Myristicin is also known to induce hallucinogenic effects, such as visual distortions. Nutmeg intoxication has an extremely long time before peak is reached, sometimes taking up to seven hours, and effects can be felt for 24 hours, with lingering effects lasting up to 72 hours.

Lima bean or  butter bean ( Phaseolus lunatus). Raw beans contain dangerous amounts of linamarin, a cyanogenic glucoside.

Onions and garlic.Onions and garlic (genus  Allium) contain thiosulphate, which in high doses is toxic to dogs, cats and some other livestock.

Potato ( Solanum tuberosum). Potatoes contain toxic compounds known as glycoalkaloids, of which the most prevalent are solanine and chaconine. Solanine is also found in other members of the Solanaceae plant family, which includes  Atropa belladonna ("deadly nightshade") and  Hyoscyamus niger ("henbane") (see entries below). The concentration of glycoalkaloid in wild potatoes suffices to produce toxic effects in humans. The toxin affects the nervous system, causing headaches, diarrhea and intense digestive disturbances, cramps, weakness and confusion, and in severe cases coma and death. Poisoning from cultivated potatoes occurs very rarely however, as the toxic compounds in the potato plant are, in general, concentrated in the green portions of the plant and in the fruits, and cultivated potato varieties contain lower toxin levels. Cooking at high temperatures (over 170 °C or 340 °F) also partly destroys the toxin. However, exposure to light, physical damage, and age increase glycoalkaloid content within the tuber, the highest concentrations occurring just underneath the skin. Tubers which are exposed to light turn green from chlorophyll synthesis, thus giving a visual clue as to areas of the tuber that may have become more toxic; however, this does not provide a definitive guide, as greening and glycoalkaloid accumulation can occur independently of each other. Some varieties of potato contain greater glycoalkaloid concentrations than others; breeders developing new varieties test for this, and sometimes have to discard an otherwise promising cultivar. Breeders try to keep solanine levels below 200 mg/kg (200 ppmw). However, when these commercial varieties turn green, even they can approach concentrations of solanine of 1000 mg/kg (1000 ppmw). The U.S. National Toxicology Program suggests that the average American consume at most 12.5 mg/day of solanine from potatoes (the toxic dose is actually several times this, depending on body weight). Douglas L. Holt, the State Extension Specialist for Food Safety at the University of Missouri, notes that no reported cases of potato-source solanine poisoning have occurred in the U.S. in the last 50 years, and most cases involved eating green potatoes or drinking potato-leaf tea

Rhubarb ( Rheum rhaponticum). The leaf stalks (petioles) are edible, but the leaves themselves contain notable quantities of oxalic acid, which is a nephrotoxic and corrosive acid that is present in many plants. Symptoms of poisoning include kidney disorders, convulsions and coma. Rarely fatal. The LD50 (median lethal dose) for pure oxalic acid in rats is about 375 mg/kg body weight, or about 25 grams for a 65 kg (~140 lb) human. While the oxalic acid content of rhubarb leaves can vary, a typical value is about 0.5%, so a rather unlikely 5 kg of the extremely sour leaves would have to be consumed to reach an LD50 of oxalic acid. Cooking the leaves with soda can make them more poisonous by producing soluble oxalates. However, the leaves are believed to also contain an additional, unidentified toxin, which might be an anthraquinone glycoside (also known as senna glycosides). In the edible leaf stalks (petioles), the amount of oxalic acid is much lower, only about 2-2.5% of the total acidity which is dominated by malic acid. This means that even the raw stalks may not be hazardous (though they are generally thought to be in the US). However the tart taste of raw stalks is so strong as to be unpalatable to many.

Tomato ( Solanum lycopersicum). Like many other nightshades, tomato leaves and stems contain solanine that is toxic if ingested, causing digestive upset and nervous excitement. Use of tomato leaves as a tea (tisane) has been responsible for at least one death. Leaves, stems, and green unripe fruit of the tomato plant also contain small amounts of the poisonous alkaloid tomatine, although levels are generally too small to be dangerous. Ripe tomatoes do not contain any detectable tomatine. Tomato plants can be toxic to dogs if they eat large amounts of the fruit, or chew plant material.

Aconitum (Several species, commonly called  aconitewolfsbane and  monkshood) All parts are poisonous. The poison is an alkaloid called aconitine, which disables nerves, lowers blood pressure, and can stop the heart. Even casual skin contact should be avoided; symptoms include numbness, tingling, and cardiac irregularity. It has been used as poison for bullets (by Germany in WWII), as a bait and arrow poison (ancient Greece), and to poison water supplies (reports from ancient Asia). If ingested, it usually causes burning, tingling, and numbness in the mouth, followed by vomiting and nervous excitement. It is usually a quick-acting poison. Used in the past for killing wolves (hence one of the common names).

Actaea pachypoda  (also known as  doll's eyes or  white baneberry). All parts are poisonous, but especially the berries, the consumption of which has a sedative effect on cardiac muscle tissue and can cause cardiac arrest.
Adenium obesum (also known as  sabi starkudu or  desert-rose). Exudes a highly toxic sap which is used by the Meridian High and Hadza in Tanzania to coat arrow-tips for hunting.

Aesculus hippocastanum (commonly known as  horse-chestnut). All parts of the plant are poisonous, causing nausea, muscle twitches, and sometimes paralysis.

Agave. The juice of a number of species causes acute contact dermatitis, with blistering lasting several weeks and recurring itching for several years thereafter.

Ageratina altissima (commonly known as  white snakeroot). All parts are poisonous, causing nausea and vomiting. Often fatal. Milk from cattle that have eaten white snakeroot can sicken, or kill, humans (milk sickness).

Aquilegia (also known as  columbine). Several species. Seeds and roots contain cardiogenic toxins which cause both severe gastroenteritis and heart palpitations if consumed. The flowers of various species were consumed in moderation by Native Americans as a condiment with other fresh greens, and are reported to be very sweet, and safe if consumed in small quantities. Native Americans also used very small amounts of the root as an effective treatment for ulcers. However, the medical use of this plant is difficult due to its high toxicity; columbine poisonings are easily fatal.

Arum maculatum (commonly known as  cuckoo-pintlords and ladiesjack in the pulpitwake robinwild arumdevils and angelscows and bullsAdam and Evebobbins and starch-root). All parts of the plant can produce allergic reactions. The bright red berries contain oxalates of saponins and can cause skin, mouth and throat irritation, resulting in swelling, burning pain, breathing difficulties and stomach upset. One of the most common causes of plant poisoning

Atropa Belladonna
Atropa belladonna (commonly known as  deadly nightshadebelladonnadevil's cherry and  dwale, an Anglo-Saxon term meaning stupifying drink). One of the most toxic plants found in the Western hemisphere. All parts of the plant contain tropane alkaloids. The active agents are atropine, hyoscine (scopolamine), and hyoscyamine, which have anticholinergic properties. The symptoms of poisoning include dilated pupils, sensitivity to light, blurred vision, tachycardia, loss of balance, staggering, headache, rash, flushing, dry mouth and throat, slurred speech, urinary retention, constipation, confusion, hallucinations, delirium, and convulsions. The root of the plant is generally the most toxic part, though this can vary from one specimen to another. Ingestion of a single leaf of the plant can be fatal to an adult.] Casual contact with the leaves can cause skin pustules. The berries pose the greatest danger to children because they look attractive and have a somewhat sweet taste. The consumption of two to five berries by children and ten to twenty berries by adults can be lethal. In 2009 a case of  A. belladonna being mistaken for blueberries, with six berries ingested by an adult woman, was documented to result in severe anticholinergic syndrome. The plant's deadly symptoms are caused by atropine's disruption of the parasympathetic nervous system's ability to  for atropine poisoning is physostigmine or pilocarpine.  A. belladonna is also toxic to many domestic animals, causing narcosis and paralysis. However, cattle and rabbits eat the plant seemingly without suffering harmful effects. In humans its anticholinergic properties will cause the disruption of cognitive capacities like memory and learning.

Caladium (commonly known as  angel wingselephant ear and  heart of Jesus). All parts of the plant are poisonous. Symptoms are generally irritation, pain, and swelling of tissues. If the mouth or tongue swell, breathing may be fatally blocked.

Cicuta (several species) (commonly known as  water hemlockcowbanewild carrotsnakeweedpoison parsnipfalse parsleychildren's bane and  death-of-man). The root, when freshly pulled out of the ground, is extremely poisonous and contains the toxin  cicutoxin, a central nervous system stimulant, resulting in seizures. When dried, the poisonous effect is reduced. The most common species is  C. maculata; one of the species found in the Western USA,  C. douglasii, often found in pastures and swamps, has especially thick stems and very large and sturdy flowers which are sometimes harvested for flower displays. This is inadvisable as the sap is also toxic.

Colchicum autumnale (commonly known as  autumn crocus and  meadow saffron). The bulbs contain colchicine. Colchicine poisoning has been compared to arsenic poisoning; symptoms start 2 to 5 hours after the toxic dose has been ingested and include burning in the mouth and throat, fever, vomiting, diarrhea, abdominal pain and kidney failure. These symptoms may set in as many as 24 hours after the exposure. Onset of multiple-system organ failure may occur within 24 to 72 hours. This includes hypovolemic shock due to extreme vascular damage and fluid loss through the GI tract, which may result in death. Additionally, sufferers may experience kidney damage resulting in low urine output and bloody urine; low white blood cell counts (persisting for several days); anemia; muscular weakness; and respiratory failure. Recovery may begin within 6 to 8 days. There is no specific antidote for colchicine, although various treatments do exist.] Despite dosing issues concerning its toxicity, colchicine is prescribed in the treatment of gout, familial Mediterranean fever, pericarditis and Behçet's disease. It is also being investigated for its use as an anti-cancer drug.

Conium maculatum (commonly known as  hemlockpoison hemlockspotted parsleyspotted cowbanebad-man's oatmealpoison snakeweed and  beaver poison). All parts of the plant contain the alkaloid coniine which causes stomach pains, vomiting, and progressive paralysis of the central nervous system. Can be fatal; it is the poison that killed Socrates. Not to be confused with hemlock trees ( Tsuga spp), which, while not edible, are not nearly as toxic as the herbaceous plant  Conium.

Consolida (commonly known as  larkspur). Young plants and seeds are poisonous, causing nausea, muscle twitches, paralysis. Often fatal.

Convallaria majalis (commonly known as  lily of the valley). Contains 38 different cardiac glycosides.

Cyano bacteria A phylum of bacteria, commonly known as  blue-green algae. Many different species, including  Anacystis cynea and  Anabaena circinalis. Produce several different toxins known collectively as cyan toxins. These can include neurotoxins, hepatotoxins, endotoxins and cytotoxins. Potentially hazardous particularly to marine animals, but also to humans.

Cytisus scoparius (commonly known as  broom or  common broom). Contains toxic alkaloids that depress the heart and nervous system. The alkaloid sparteine is a class 1antiarrhythmic agent; a sodium channel blocker. It is not FDA approved for human use as an ant arrhythmic agent, and it is not included in the Vaughn Williams classification of ant arrhythmic drugs.

Datura Contains the alkaloids scopolamine and atropine. Datura has been used as a hallucinogenic drug by the native peoples of the Americas and others. Incorrect dosage can lead to death.

Datura stramonium (commonly known as  jimson weedthorn applestinkweed and  Jamestown weed). All parts of the plant are poisonous, causing abnormal thirst, vision distortions, delirium, incoherence, coma. Often fatal. A significant grazing livestock poison in North America.

Delphinium (also known as  larkspur). Contains the alkaloid delsoline. Young plants and seeds are poisonous, causing nausea, muscle twitches, paralysis, often fatal.

Dicentra cucullaria (also known as  bleeding heart and  Dutchman's breeches). Leaves and roots are poisonous and cause convulsions and other nervous symptoms.

Digitalis purpurea (commonly known as  foxglove). The leaves, seeds, and flowers are poisonous, containing cardiac or other steroid glycosides. These cause irregular heartbeat, general digestive upset, and confusion. Can be fatal.

Hedera helix (or  common ivy) The leaves and berries are poisonous, causing stomach pains, labored breathing, possible coma.
Heracleum mantegazzianum (also known as  giant hogweed). The sap is phototoxic, causing phytophotodermatitis (severe skin inflammations) when affected skin is exposed to sunlight or to UV-rays. Initially the skin colors red and starts itching. Then blisters form as reaction continues over 48 hours. They form black or purplish scars, which can last several years. Hospitalization may become necessary. Presence of minute amounts of sap in the eyes can lead to temporary or even permanent blindness.

Hyacinthus orientalis (commonly known as  hyacinth). The bulbs are poisonous, causing nausea, vomiting, gasping, convulsions, and possibly death. Even handling the bulbs can cause skin irritation.

Hyoscyamus niger (commonly known as  henbane). Seeds and foliage contain hyoscyamine, scopolamine and other tropane alkaloids. Can produce dilated pupils, hallucinations, increased heart rate, convulsions, vomiting, hypertension and ataxia.

Ilex aquifolium (commonly known as  European holly). The berries cause gastroenteritis, resulting in nausea, vomiting and diarrhoea.

Jacobaea vulgaris
Jacobaea vulgaris (commonly known as  ragwort). Contains many different alkaloids, including jacobine, jaconine, jacozine, otosenine, retrorsine, seneciphylline, senecionine, and senkirkine. poisonous to livestock and hence of concern to people who keep horses and cattle. Horses do not normally eat fresh ragwort due to its bitter taste, however it loses this taste when dried, and become dangerous in hay. The result, if sufficient quantity is consumed, can be irreversible cirrhosis of the liver. Signs that a horse has been poisoned include yellow mucus membranes, depression, and lack of coordination. The danger is that the toxin can have a cumulative effect; the alkaloid does not actually accumulate in the liver but a breakdown product can damage DNA and progressively kills cells.  Jacobaea vulgaris is also theoretically poisonous to humans, although poisoning is unlikely as it is distasteful and not used as a food. However some sensitive individuals can suffer from an allergic skin reaction after handling the plant because, like many members of the compositae family, it contains sesquiterpine lactones (which are different from the pyrrolizidine alkaloids which are responsible for the toxic effects), which can cause compositae dermatitis.

Kalmia latifolia (commonly known as  mountain laurel). Contains and romedotoxin and arbutin. The green parts of the plant, flowers, twigs, and pollen are all toxic, and symptoms of toxicity begin to appear about 6 hours following ingestion. Poisoning produces anorexia, repeated swallowing, profuse salivation, depression, decoordination, vomiting, frequent defecation, watering of the eyes, irregular or difficulty breathing, weakness, cardiac distress, convulsions, coma, and eventually death. Autopsy will show gastrointestinal irritation and hemorrhage.

Laburnum. All parts of the plant and especially the seeds are poisonous and can be lethal if consumed in excess. The main toxin is cytisine, a nicotinic receptor agonist. Symptoms of poisoning may include intense sleepiness, vomiting, excitement, staggering, convulsive movements, slight frothing at the mouth, unequally dilated pupils, coma and death. In some cases, diarrhea is very severe and at times the convulsions are markedly tetanic.

Ligustrum (several species, commonly known as  privet). Berries and leaves are poisonous. Berries contain syringing, which causes digestive disturbances, nervous symptoms. Can be fatal. Privet is one of several plants which are poisonous to horses. Privet pollen is known to cause asthma and eczema in sufferers. It is banned from sale or cultivation in New Zealand due to the effects of its pollen on asthma sufferers.

Lilium (commonly known as  lily). Most have an unknown water-soluble toxin found in all parts of the plant. Extremely poisonous, yet attractive, to cats, causing acute renal failure; 2 petals can kill.

Lolium temulentum (commonly called  darnel or  poison ryegrass). The seeds and seed heads of this common garden weed may contain the alkaloids temuline and loliine. Some experts also point to the fungus ergot or fungi of the genus endoconidium, both of which grow on the seed heads of rye grasses, as an additional source of toxicity.

Mango tree – Mango peel and sap contains urushiol, the chemical in poison ivy and poison sumac that can cause urushiol-induced contact dermatitis in susceptible people. Cross-reactions between mango contact allergens and urushiol have been observed. Those with a history of poison ivy or poison oak contact dermatitis may be most at risk for such an allergic reaction. Urushiol is also present in mango leaves and stems. During mango's primary ripening season, it is the most common source of plant dermatitis in Hawaii.

Narcissus (commonly known as  daffodil). Various species and garden cultivars. The bulbs are poisonous and cause nausea, vomiting, and diarrhea. Can be fatal. Stems also cause headaches, vomiting, and blurred vison

Nerium oleander (commonly known as  oleander). All parts are toxic, but especially the leaves and woody stems. Contains nerioside, oleandroside, saponins and cardiac glycosides. Causes severe digestive upset, heart trouble and contact dermatitis. The smoke of burning oleander can cause reactions in the lungs, and can be fatal.

Podophyllum peltatum (commonly known as  mayapple). Green portions of the plant, unripe fruit, and especially the rhizome contain the non-alkaloid toxin podophyllotoxin, which causes diarrhea, severe digestive upset.

Quercus (several species, commonly known as  oak). The leaves and acorns of oak species are poisonous in large amounts to humans and livestock, including cattle, horses, sheep and goats, but not pigs. Poisoning is caused by the toxin tannic acid, which causes gastroenteritis, heart trouble, contact dermatitis and kidney damage. Symptoms of poisoning include lack of appetite, depression, constipation, diarrhea (which may contain blood), blood in urine, and colic. Rarely fatal however, and in fact after proper processing acorns are consumed as a staple in many parts of the world.

Rhododendron (certain species commonly known as  Azaleas). All parts are poisonous and cause nausea, vomiting, depression, breathing difficulties, coma. Rarely fatal.

Ricinus communis aka Wild Castor Oil Plant
Ricinus communis (commonly known as  castor oil plant or  Palma Christi). The seeds contain ricin, an extremely toxic water-soluble protein. Also present are ricinine, an alkaloid, and an irritant oil. According to the 2007 edition of the Guinness Book of World Records, this plant is the most poisonous in the world. Castor oil, long used as a laxative, muscle rub, and in cosmetics, is made from the seeds, but the ricin is removed during processing. The lethal dose in adults is considered to be 4 to 8 seeds, but reports of actual poisoning are relatively rare. If ingested, symptoms may be delayed by up to 36 hours but commonly begin within 2–4 hours. These include a burning sensation in mouth and throat, abdominal pain, purging and bloody diarrhea. Within several days there is severe dehydration, a drop in blood pressure and a decrease in urine. Unless treated, death can be expected to occur within 3–5 days; if victims have not succumbed after this time, they often recover. In 1978, ricin was used to assassinate Georgi Markov, a Bulgarian dissident. He was stabbed with the point of an umbrella while waiting at a bus stop near Waterloo Station in London. After his death a perforated metallic pellet was found embedded in his leg; this had presumably contained the ricin toxin. Toxicity varies among animal species: 4 seeds will kill a rabbit, 5 a sheep, 6 an ox or horse, 7 a pig, and 11 a dog. Poisoning occurs when animals ingest broken seeds or break the seed by chewing; intact seeds may pass through the digestive tract without releasing the toxin. Ducks have shown substantial resistance to the seeds: it takes an average of 80 to kill them.

Sambucus (commonly known as  elder or  elderberry). The roots are considered poisonous and cause nausea and digestive upset.
Sanguinaria canadensis (commonly known as  bloodroot). The rhizome contains morphine-like benzylisoquinoline alkaloids, primarily the toxin sanguinarine. Sanguinarine kills animal cells by blocking the action of Na+/K+-ATPase transmembrane proteins. As a result, applying  S. canadensis to the skin may destroy tissue and lead to the formation of a large scab, called an eschar. Although applying escharotic agents, including  S. canadensis, to the skin is sometimes suggested as a home treatment for skin cancer, these attempts can be severely disfiguring,as well as unsuccessful. Case reports have shown that in such instances tumor has recurred and/or metastasized. The United States Food and Drug Administration (FDA) has approved the inclusion of sanguinarine in toothpastes as an antibacterial or anti-plaque agent, although it is believed that this use may cause leukoplakia, a premalignant oral lesion. The safe level of sanguinarine in such products is subject to regulation and debate.  S. canadensis extracts have also been promoted by some supplement companies as a treatment or cure for cancer, but the FDA has listed some of these products among its "187 Fake Cancer 'Cures' Consumers Should Avoid". Bloodroot is a popular red natural dye used by Native American artists, especially among southeastern river cane basket makers. However in spite of supposed curative properties and historical use by Native Americans as an emetic, due to its toxicity internal use is not advisable (sanguinarine has an LD50 of only 18 mg per kg body weight).

Taxus baccata (commonly known as  English yew', common yew and  graveyard tree). Nearly all parts contain toxic taxanes (except the red, fleshy, and slightly sweet aril surrounding the toxic seeds). The seeds themselves are particularly toxic if chewed. Several people have committed suicide by ingesting leaves and seeds, including Catuvolcus, king of a tribe in what is now Belgium.

Toxicodendron Several species, including  Toxicodendron radicans (commonly known as  poison ivy),  Toxicodendron diversilobum (commonly known as  poison-oak), and Toxicodendron vernix (commonly known as  poison sumac). All parts of these plants contain a highly irritating oil with urushiol. Skin reactions can include blisters and rashes. It spreads readily to clothes and back again, and has a very long life. Infections can follow scratching. Despite the common names, urushiol is actually not a poison but an allergen, and because of this it will not affect certain people. The smoke of burning poison ivy can cause reactions in the lungs, and can be fatal.

False Hellebore aka Corn Lily
Veratrum (commonly known as  false hellebore and  corn lily). Several species, containing highly toxic steroidal alkaloids (e.g. veratridine) that activate sodium ion channels and cause rapid cardiac failure and death if ingested. All parts of the plant are poisonous, with the root and rhizomes being the most toxic. Symptoms typically occur between 30 minutes and 4 hours after ingestion and include nausea and vomiting, abdominal pain, numbness, headache, sweating, muscle weakness, bradycardia, hypotension, cardiac arrhythmia, and seizures. Treatment for poisoning includes gastrointestinal decontamination with activated charcoal followed by supportive care including fluid replacement, antiemetics for persistent nausea and vomiting, atropine for treatment of bradycardia, and vasopressors for the treatment of hypotension. Native Americans used the juice pressed from the roots to poison arrows before combat. The dried powdered root of this plant was also used as an insecticide. The plants' teratogenic properties and ability to induce severe birth defects were well known to Native Americans, although they also used minute amounts of the winter-harvested root (combined with  Salvia dorii to potentiate its effects and reduce the toxicity of the herb) to treat cancerous tumors. The toxic steroidal alkaloids are produced only when the plants are in active growth, so herbalists and Native Americans who used this plant for medicinal purposes harvested the roots during the winter months when the levels of toxic constituents were at their lowest. The roots of  V. nigrum and  V. schindleri have been used in Chinese herbalism (where plants of this genus are known as "li lu" (藜蘆). Li lu is used internally as a powerful emetic of last resort, and topically to kill external parasites, treat tinea and scabies, and stop itching. However some herbalists refuse to prescribe li lu internally, citing the extreme difficulty in preparing a safe and effective dosage, and that death has occurred at a dosage of 0.6 grams. During the 1930s  Veratrum extracts were investigated in the treatment of high blood pressure in humans. However patients often suffered side effects due to the narrow therapeutic index of these products. Due to its toxicity, the use of  Veratrum as a treatment for high blood pressure in humans was discontinued.

Xanthium aka Cocklebur
Xanthium (commonly known as  cocklebur). Several species. The Common Cocklebur ( X. strumarium), a native of North America, can be poisonous to livestock, including horses, cattle, and sheep. Some domestic animals will avoid consuming the plant if other forage is present, but less discriminating animals, such as pigs, will consume the plants and then sicken and die. The seedlings and seeds are the most toxic parts of the plants. Symptoms usually occur within a few hours, producing unsteadiness and weakness, depression, nausea and vomiting, twisting of the neck muscles, rapid and weak pulse, difficulty breathing, and eventually death.  Xanthium has also been used for its medicinal properties and for making yellow dye, as indicated by its name (Greek  xanthos = 'yellow')

Zantedeschia (several species, also known as  Lily of the Nile and  Calla lily). Contain calcium oxalate. All parts of the plant are toxic, producing irritation and swelling of the mouth and throat, acute vomiting and diarrhoea. Can be fatal.

Credit: Images for this blog post were sourced from Wikimedia Commons and are public domain images.