Plant
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...
s that produce
toxin
A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849– ...
s are referred to as poisonous plants. Plants that cause irritation on contact are also described as "poisonous".
The toxins in poisonous plants affect
herbivore
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
s, and deter them from consuming the plants. Plants cannot move to escape their predators, so they must have other means of protecting themselves from herbivorous animals. Some plants have physical defenses such as
thorns, spines and prickles
In plant morphology, thorns, spines, and prickles, and in general spinose structures (sometimes called ''spinose teeth'' or ''spinose apical processes''), are hard, rigid extensions or modifications of leaves, roots, stems or buds with sharp, sti ...
, but by far the most common type of protection is chemical.
Over millennia, through the process of
natural selection
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charle ...
, plants have
evolved
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation t ...
the means to produce a vast and complicated array of chemical compounds to deter herbivores.
Tannin
Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids.
The term ''tannin'' (from Anglo-Norman ''tanner'', ...
, for example, is a defensive compound that emerged relatively early in the evolutionary history of plants, while more complex molecules such as
polyacetylenes are found in younger groups of plants such as the
Asterales
Asterales () is an order of dicotyledonous flowering plants that includes the large family Asteraceae (or Compositae) known for composite flowers made of florets, and ten families related to the Asteraceae. While asterids in general are chara ...
. Many of the known
plant defense compounds primarily defend against consumption by
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s, though other animals, including humans, that consume such plants may also experience negative effects, ranging from mild discomfort to death.
Many of these poisonous compounds also have important
medicinal
Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care practic ...
benefits. The varieties of
phytochemical
Phytochemicals are chemical compounds produced by plants, generally to help them resist fungi, bacteria and plant virus infections, and also consumption by insects and other animals. The name comes . Some phytochemicals have been used as poisons ...
defenses in plants are so numerous that many questions about them remain unanswered, including:
# Which plants have which types of defense?
# Which herbivores, specifically, are the plants defended against?
# What chemical structures and mechanisms of toxicity are involved in the compounds that provide defense?
# What are the potential medical uses of these compounds?
These questions and others constitute an active area of research in modern
botany
Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...
, with important implications for understanding plant evolution and medical science.
Below is an extensive, if incomplete, list of plants containing one or more poisonous parts that pose a serious risk of illness, injury, or death to humans or domestic animals. There is significant overlap between plants considered poisonous and those with
psychotropic properties, some of which are toxic enough to present serious health risks at recreational doses. There is a distinction between plants that are poisonous because they naturally produce dangerous phytochemicals, and those that may become dangerous for other reasons, including but not limited to infection by bacterial, viral, or fungal parasites; the uptake of
toxic compounds through contaminated soil or groundwater; and/or the ordinary processes of decay after the plant has died; this list deals exclusively with plants that produce phytochemicals. Many plants, such as
peanut
The peanut (''Arachis hypogaea''), also known as the groundnut, goober (US), pindar (US) or monkey nut (UK), is a legume crop grown mainly for its edible Seed, seeds. It is widely grown in the tropics and subtropics, important to both small ...
s, produce compounds that are only dangerous to people who have developed an
allergic reaction
Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derma ...
to them, and with a few exceptions, those plants are not included here (see
list of allergens
This is a list of allergies, which includes the allergen, potential reactions, and a brief description of the cause where applicable.
Allergens
Food
Medical
Environmental
Contact
Many substances can cause an allergic reaction when in c ...
instead). Despite the wide variety of plants considered poisonous, human fatalities caused by poisonous plants – especially resulting from accidental ingestion – are rare in the developed world.
[Krenzelok EP, Mrvos R.,"Friends and foes in the plant world: A profile of plant ingestions and fatalities." Clin Toxicol. 2011 Mar;49(3):142-149]
Poisonous plants that are food
Many plants commonly used as food possess toxic parts, are toxic unless processed, or are toxic at certain stages of their lives. Some only pose a serious threat to certain animals (such as cats, dogs, or
livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animals ...
) or certain types of people (such as infants, the elderly, or individuals with pathological vulnerabilities). Most of these food plants are safe for the average adult to eat in modest quantities. Notable examples include:
Other poisonous plants
Countless other plants not commonly used in food or drink are also poisonous, and care should be taken to avoid accidentally contacting or ingesting them. Some of these are popular ornamental plants or are cultivated for purposes other than consumption.
See also
*
List of plants poisonous to equines
Many plants are poisonous to equines; the species vary depending on location, climate, and grazing conditions. In many cases, entire genera are poisonous to equines and include many species spread over several continents. Plants can cause reactio ...
*
List of poisonous fungus species
This is a compendium of poisonous fungi. See also mushroom poisoning.
List of toxic mushroom species
''There are poisonous fungus species listed below.''
List of suspicious mushroom species
See also
*List of deadly fungi
*List of poisonous a ...
*
List of venomous animals
Numerous animal species naturally produce chemical toxins which are used to kill or incapacitate prey or as a defense against predators.
Venomous animals actively deliver their toxins (called venom) into their target through a specially evolved ...
*
Biopesticide
A Biopesticide is a biological substance or organism that damages, kills, or repels organisms seens as pests. Biological pest management intervention involves predatory, parasitic, or chemical relationships.
They are obtained from organisms inclu ...
*
Mushroom poisoning
Mushroom poisoning is poisoning resulting from the ingestion of mushrooms that contain toxic substances. Its symptoms can vary from slight gastrointestinal discomfort to death in about 10 days. Mushroom toxins are secondary metabolites produced by ...
*
Psychoactive plant
Psychoactive plants are plants, or preparations thereof, that upon ingestion induce psychotropic effects. As stated in a reference work:
Psychoactivity may include sedative, stimulant, euphoric, deliriant, and hallucinogenic effects.
Several ...
*
Secondary metabolite
Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the norm ...
*
Toxin
A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849– ...
*
Weed
A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...
References
Bibliography
*
External links
US Army: Guide to poisonous and toxic plantsCornell University Poisonous Plants Information Databasepo
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Poisonous
Poison is a chemical substance that has a detrimental effect to life. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figuratively, with a broa ...
Poisonous
Poison is a chemical substance that has a detrimental effect to life. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figuratively, with a broa ...
Poisonous
Poison is a chemical substance that has a detrimental effect to life. The term is used in a wide range of scientific fields and industries, where it is often specifically defined. It may also be applied colloquially or figuratively, with a broa ...
Toxicology
Hazards of outdoor recreation
Poisonous plants