Nightshades are a group of flowering plants from the Solanaceae family. This large, diverse family comprises more than 90 genera and 2,700 species. Nightshade plants are distributed on all major continents except Antarctica, with the highest concentration of species found in Central and South America.
Nightshades range from small herbs, weeds, and vines to shrubs, trees, and other plants. While the majority of nightshade species are inedible, the edible nightshade vegetables include a number of important agricultural crops such as potatoes, tomatoes, eggplants, peppers, and tobacco.
Some nightshades, such as ashwagandha, have tremendous medicinal value, while others are psychoactive or poisonous, including jimsonweed and belladonna, respectively.
What are Nightshade Vegetables?
Nightshade vegetables are the edible parts (fruits and tubers) of flowering plants in the Solanaceae family. Many nightshade vegetables are economically important crops that are foundational to many diets around the world.
Some common edible nightshade vegetables include:
- Bell peppers
- Chile peppers
- Sweet peppers
- Habanero peppers
- Jalapeño peppers
In addition, some of these nightshade vegetables are the basis for many herbs, spices, and spice mixtures, including paprika, cayenne pepper, crushed red pepper, and chile powder. Since they bear seeds, tomatoes, eggplants, and peppers are botanically classified as fruits, though they are widely referred to as vegetables in the culinary sense.
What Makes a Plant a Nightshade?
The nightshade family members are annuals, biennials, or perennials that take a variety of forms, including herbs, vines, shrubs, lianas, epiphytes, and trees. They are characterized by flowers with five petals, sepals, and stamens. The flowers may be star-shaped or round and flat, but are commonly bell-shaped or tubular. Generally, nightshades have alternate leaves that grow in a staggered fashion around a hairy stem. The leaves are usually simple and can be inodorous or aromatic. Nightshade fruits are usually berries, but sometimes dry or fleshy capsules.
Solanaceous plants are known for producing a diverse range of biologically active alkaloids. These alkaloids are used by the plant as a natural pesticide, helping it to defend against insects and mold. For humans, nightshade alkaloids may have medicinal value or are hallucinogenic, poisonous, or both.
Toxic vs. Psychoactive Alkaloids
The genera Atropa, Datura, and others contain potent tropane alkaloids such as atropine, scopolamine, and hyoscyamine. These alkaloids are powerful anticholinergic compounds that work by inhibiting neural impulses of the endogenous neurotransmitter acetylcholine. While known for their toxic properties, they’ve been used historically for their hallucinogenic properties and medicinal effects as an antispasmodic and mydriatic. The genus Solanum (which includes tomatoes, eggplants, and potatoes) contains an alkaloid called solanine. Solanine generally doesn’t cause toxic effects when Solanum vegetables are consumed in typical quantities, barring allergies and intolerances. It is poisonous in large quantities, however, such as in the case of green potatoes that have been exposed to sunlight.
Hot Peppers and Nicotine
The pepper genus Capsicum contains the alkaloid capsaicin, which produces the characteristic burning sensation associated with chile peppers and spices. The nightshade tobacco plant, Nicotiana tabacum, produces large quantities of nicotine, a stimulant alkaloid produced by the plant as a potent neurotoxin against insects. Eggplants, tomatoes, potatoes, and peppers also contain nicotine, but at levels many orders of magnitude lower than the tobacco plant.
What Happens if You Touch Nightshade?
The majority of nightshade plants, especially the edible varieties, can be touched safely and won’t cause any problems. However, certain poisonous varieties, such as black henbane, mandrake, and deadly belladonna, can cause skin irritation and rashes when touched. This is especially the case if the skin that makes contact with the plant has cuts or other wounds. For this reason, these poisonous plants are best handled with gloves.
What Happens if You Eat Nightshade?
Many edible nightshades, such as potatoes, tomatoes, eggplants, and peppers, have been staple foods for millennia. These varieties are nutrient-rich and are well tolerated in most individuals that don’t have allergies or intolerances.
However, the vast majority of nightshade species are inedible and potentially poisonous. Many varieties, such as bittersweet nightshade, mandrake, henbane, and Carolina horsenettle, can cause toxic adverse effects when ingested. These include headache, disorientation, hallucinations, tachycardia, and gastrointestinal symptoms. While fatal intoxications with these plants are rare, it does happen in children or when large enough quantities are consumed.
When deadly nightshade (Atropa belladonna) is eaten, the poisonous tropane alkaloids (which are found in the entirety of the plant) can result in a potentially fatal condition called anticholinergic syndrome. This syndrome is characterized by dilated pupils, sensitivity to light, blurred vision, convulsions, headache, delirium, tachycardia, hallucinations, coma, and death. Eating just a few berries from deadly nightshade can kill a child, and 10 to 20 berries can kill an adult.
Common Nightshade Plants & Vegetables
Potatoes are starchy tubers from the Solanum tuberosum plant. S. tuberosum is an annual that is indigenous to the Peruvian-Bolivian Andes. After being domesticated in Peru at least 8,000 years ago, potatoes have since spread around the world and become a globally important staple food. Currently, there are over 5,000 potato varieties as a result of selective breeding over the millennia. In 2018, over 368 metric tons of potatoes were produced around the world, with China comprising 27% of the total production. Potatoes are highly digestible and a rich source of vitamins, minerals, and fiber. Ingestion of green potatoes, however, can cause potentially severe symptoms due to high levels of solanine.
Tomatoes are the ripe fruit (berry) of the flowering plant Solanum lycopersicum. S. lycopersicum originated in western South America and is now cultivated in temperate climates around the world, commonly in greenhouses year-round. The climbing vine grows up to 3 meters in height and produces yellow flowers and usually red fruits (though many other varieties exist). Aztecs domesticated and cultivated the wild species in Pre-Columbian Mexico over 2,500 years ago. Indeed, the word “tomato” comes from the Nahuatl (the Aztecan language) word tomatl. The Spaniards then brought the tomato to Europe in the 16th century after colonizing Mexico.
In 2018, approximately 188 million metric tons of tomatoes were produced worldwide, with China responsible for over a third of the total production. While the fruit is highly nutritious—containing a good source of vitamins A and C and the antioxidant lycopene—the roots and leaves of the tomato plant are poisonous since they contain solanine.
Ashwagandha, or Withania somnifera, is an adaptogenic plant commonly used as a medicinal herb in Ayurvedic medicine. The word ashwagandha comes from the Sanskrit words “ashva” meaning horse, and “gandha” meaning smell, indicating the horse-like odor of the medicinal root. Ashwagandha is a perennial shrub that is native to India, Nepal, China, and Yemen. It grows up to 30 inches tall and blooms small, green, bell-shaped flowers. Bioactive compounds called withanolides give it its medicinal properties. Studies support its medicinal use in decreasing stress and anxiety, improving strength performance, increasing glucose metabolism, and enhancing testosterone production.
Tobacco is the common name referring to several species in the Nicotiana genus. These plants contain the stimulant alkaloid nicotine in nearly all parts of the plant except for the seeds. Chief among the more than 70 Nicotiana species is the Nicotiana tabacum plant. While native to the Caribbean, N. tabacum is grown commercially throughout the world in order to harvest the leaves for a variety of tobacco products. Many other species of tobacco are grown as ornamental plants, while still others have been used as model organisms in genetic studies.
Petunias are a genus of 20 flowering plants that are native to South America. They were introduced to Europe in the 19th century and are nowadays cultivated in many parts of the world as ornamental plants. They bloom tubular flowers in a wide range of bright colors that are largely pollinated by insects. The common garden petunia is an annual, blooming from spring until frost. Many petunia varieties found in gardens around the world are hybrids.
Datura is a genus of nine poisonous flowering plants that are endemic to Mexico and subtropical regions of the Americas. The most popular species are D. stramonium (jimsonweed), D. metel, and D. inoxia. The plants grow up to two meters in height and produce large, trumpet-shaped flowers that range in color from white to pale purple. Datura’s beautiful, fragrant flowers pop open at dusk and wilt by mid-morning. They have a long history of use as a medicinal herb, poison, and psychedelic due to the tropane alkaloids (atropine, scopolamine, and hyoscyamine) present in the seeds and flowers. Being a potent deliriant, Datura’s psychoactive effects are largely considered unpleasant and potentially dangerous.
Deadly Nightshade Plants to Watch For
Deadly nightshade or belladonna (scientific name: Atropa belladonna) is a deadly poisonous nightshade species native to much of the northern hemisphere, including Europe, Western Asia, and North Africa. It is a perennial bushy herb that grows up to five feet tall in arid wooded and roadside areas. It is characterized by green, oval leaves, greenish-purple flowers, and shiny dark purple berries. The plant has long been used as a medicine in low doses and, in high doses, as a poison by assassins. All parts of the plant (especially the berries) contain toxic tropane alkaloids such as atropine, hyoscyamine, and scopolamine. Due to its high concentration of these alkaloids, it is a main commercial source for clinical anticholinergic drugs.
Carolina horsenettle, or Solanum carolinense, is a weed-like perennial that grows primarily in the southeastern United States in pastures, on roadsides, and in disturbed areas. It grows up to three feet tall, has white or purple flowers, spiny stems, and bears a yellow tomato-like fruit. All parts of the plant, including the berries which can be easily mistaken for unripe cherry tomatoes, contain poisonous alkaloids, namely solanine. Ingestion of the plant can cause gastrointestinal symptoms, paralysis, hallucinations, respiratory depression, and death.
Black henbane, or Hyoscyamus niger, is a poisonous nightshade species originally from Europe and northern Africa but found throughout the world today. It grows in pastures, meadows, and roadside areas. The plant produces a foul odor and blooms tubular brownish-yellow flowers with a purple center. Similar to deadly nightshade, all parts of the plant (including the roots) contain toxic tropane alkaloids such as atropine, scopolamine, and hyoscyamine. Black henbane has a long history of use in traditional and folk medicine for conditions such as rheumatism, cough, asthma, stomach pain, and toothaches. In addition, in ancient times it was used in combination with other plants (such as Datura) to make hallucinogenic “magic brews” and anesthetic potions. Black henbane poisoning can cause blurred vision, hallucinations, dilated pupils, convulsions, vomiting, headache, coma, and death.
How Do I Kill Deadly Nightshade in My Garden?
Deadly nightshade can be eradicated from the garden by hand-pulling them (with gloves) from the roots. A sharp spade can be handy to remove as much of the root structure as possible. The plant can then be bagged and disposed of in the garbage. If there is a lot of it growing, an herbicide such as glyphosate can be used effectively. The herbicide method works best when it’s not going to rain for at least a day.
Is There a Cure for Deadly Nightshade Poisoning?
Deadly nightshade poisoning is largely treated symptomatically. Gastrointestinal decontamination with activated charcoal can remove the toxins if ingestion has occurred in the past few hours. In more severe cases, the anticholinergic syndrome produced by the poisoning can be treated with physostigmine, an acetylcholinesterase inhibitor.
What Are The Symptoms of Nightshade Intolerance?
People with a nightshade intolerance are unable to digest edible nightshades properly. They may have a sensitivity to glycoalkaloids (such as solanine) present in the nightshades. This intolerance can lead to symptoms such as bloating, gas, nausea, diarrhea, heartburn, and fatigue. In severe cases, nightshade intolerance can cause inflammatory reactions such as eczema, joint pain, digestive pain, and breathing problems. People with autoimmune conditions and inflammatory disorders are more likely to have nightshade intolerance.
RS Contributing Author: Dylan Beard
Dylan Beard is a freelance science writer and editor based in the beautiful Pacific Northwest. After finishing his physics degree and dabbling in neuroscience research at UC Santa Barbara in 2017, he returned to his first love: writing. As a long-term fan of the human brain, he loves exploring the latest research on psychedelics, nootropics, psychology, consciousness, meditation, and more. When not writing, you can probably find him on hiking trails around Oregon and Washington or listening to podcasts. Feel free to follow him on Insta @dylancb88.