American nightshade (Solanum americanum) is often confused with other plants in the nightshade family. It is considered toxic, though the degree of danger varies significantly. Toxicity is concentrated in specific parts of the plant and changes with the maturity of the fruit, making identification and caution paramount.
Identifying American Nightshade
American nightshade is an erect herbaceous plant or small shrub, typically reaching up to four feet tall. It commonly grows as a weed in disturbed soils, gardens, and waste areas. Its stems are green and often angular, supporting dark green, ovate or lance-shaped leaves that may feel slightly hairy underneath.
The flowers are small, star-shaped, and white, featuring five backward-curving petals around a yellow central cone. These flowers produce the plant’s characteristic fruit, which develops in clusters rather than singly. Berries start as small green spheres before maturing into a glossy, shiny black or dark purplish-black color.
Chemical Source of Toxicity
The toxicity of American nightshade is due to steroidal glycoalkaloids, natural toxins common in the Solanum genus. Specific compounds include solanine, solasonine, and solamargine. These toxins disrupt cell membrane integrity, potentially leading to tissue damage upon ingestion.
The concentration of these glycoalkaloids is highest in the leaves and the unripe, green berries. Unripe fruit is unambiguously toxic due to high solanine levels. As the fruit matures and turns shiny black, the glycoalkaloid concentration decreases substantially, sometimes to negligible levels. However, the entire plant should still be treated with caution, as even small amounts of the green fruit are highly toxic.
Clinical Signs of Poisoning
Ingestion of toxic parts primarily affects the gastrointestinal and nervous systems. Initial symptoms, appearing within six hours, often involve gastrointestinal distress. These typically include nausea, vomiting, abdominal pain, colic, and diarrhea.
Symptoms can progress to neurological effects, especially after consuming large quantities or highly toxic green berries. Individuals may experience headache, dizziness, weakness, and drowsiness. More severe, though less common, cases involve muscle tremors, confusion, slurred speech, or dilated pupils. In rare instances, severe poisoning can lead to respiratory depression, shock, or death.
Immediate Safety Measures
If there is any suspicion that an individual has ingested parts of the American nightshade plant, immediate action is necessary. Do not wait for symptoms to develop before seeking assistance. The first step is to contact a medical professional or a poison control center immediately by calling the national Poison Help Line.
Be prepared to provide specific details about the exposure to medical personnel. This information should include the part of the plant consumed (leaf or berry) and the maturity of the fruit (green or black). Also, estimate the amount and time of ingestion, and note any observed symptoms, even if they seem mild. Collecting a sample of the plant is also helpful to aid in positive identification.