The belief that a flower is “not edible” is a safety warning, signifying that the plant contains compounds capable of causing harm, ranging from mild irritation to life-threatening toxicity. This distinction focuses on the presence of natural chemical defenses evolved by the plant. Understanding which garden and indoor flowers pose a risk is a matter of safety, particularly in households with curious children or pets. Identifying these toxic varieties promotes awareness and prevents accidental exposure.
Mechanisms of Floral Toxicity
Plant toxicity arises from secondary metabolites, chemical compounds produced primarily for defense against herbivores and pests. These substances interfere significantly with the biological processes of animals that consume them. Several major groups are responsible for the most common floral poisonings.
One potent group is the cardiac glycosides, which directly affect the heart and circulatory system. These compounds inhibit the sodium-potassium ATPase pump in cell membranes, disrupting the balance of electrolytes. This interference can lead to severe gastrointestinal distress, vision disturbances, and potentially fatal irregular heart rhythms.
Another broad category is the alkaloids, nitrogen-containing compounds that act on the central nervous system. Different alkaloids can produce varied effects, such as neurological symptoms like dizziness, confusion, or seizures, or cause gastrointestinal upset. Plants also employ mechanical defenses like oxalates, microscopic, needle-shaped calcium oxalate crystals. When chewed, these crystals are propelled into the soft tissues of the mouth and throat, causing immediate, intense burning, pain, and swelling.
Identifying Highly Dangerous Varieties
Many common garden and indoor plants contain dangerous compounds, making identification necessary for safety. Among the most notorious is Oleander (Nerium oleander), a shrub whose entire structure—leaves, stems, flowers, and nectar—contains powerful cardiac glycosides. Ingestion of even a small amount can be lethal, making it one of the most toxic plants grown in warm climates.
Foxglove (Digitalis purpurea), recognizable by its tall spikes of tubular flowers, is the source of the heart medication digoxin, but all parts contain toxic cardiac glycosides. Lily of the Valley (Convallaria majalis) produces small, fragrant, bell-shaped flowers and bright red berries, all containing cardioactive toxins that can cause heart rhythm abnormalities. The water in a vase containing cut Foxglove or Lily of the Valley can also become toxic.
Lilies pose a unique and severe threat to cats, specifically those in the Lilium (e.g., Easter Lily, Tiger Lily, Stargazer Lily) and Hemerocallis (Daylily) genera. Ingestion of any part of these “true lilies” can cause rapid and severe kidney failure in felines. Peace Lilies (Spathiphyllum) and Calla Lilies contain insoluble calcium oxalates, which cause intense oral irritation but do not carry the same risk of systemic organ failure for cats.
Recognizing Poisoning Symptoms and Emergency Steps
Plant poisoning symptoms often manifest in distinct ways; the severity depends on the plant, the amount consumed, and the individual. Gastrointestinal symptoms are the most common initial response, including nausea, vomiting, abdominal pain, and diarrhea, as the body attempts to expel the toxin. Neurological symptoms may follow, presenting as dizziness, confusion, disorientation, or convulsions and seizures, depending on the chemical class of the poison.
Dermatological reactions are also possible from contact with certain plants, ranging from skin redness and irritation to blistering. If a plant containing oxalate crystals is chewed, the intense pain and swelling in the mouth and throat are immediate and can cause difficulty breathing. Symptoms involving the heart, such as a dangerously slow or irregular heartbeat, signal a life-threatening emergency from cardiac glycosides.
If accidental ingestion or contact with a potentially toxic flower occurs, immediate action is necessary. The first step is to call the national Poison Help line at 1-800-222-1222, which connects to a local Poison Control Center. Do not induce vomiting unless specifically instructed to do so by a medical professional or the Poison Control expert. Be prepared to provide specific information, including the person’s age and weight, the name of the plant if known, the part consumed (e.g., flower, berry, leaf), and the approximate time and amount of ingestion.