Differentiating Between Toxic and Non-Toxic Laurel Varieties
The name 'laurel' can be misleading, as it is applied to a variety of plants, some toxic and some not. For home gardeners and parents, it is crucial to know the difference. The highly toxic varieties are primarily garden shrubs like Cherry Laurel (Prunus laurocerasus) and Mountain Laurel (Kalmia latifolia), which contain dangerous compounds. In contrast, the true Bay Laurel (Laurus nobilis), used for culinary purposes, is generally safe for humans when used in cooking.
The Highly Toxic Varieties and Their Dangers
Cherry Laurel (Prunus laurocerasus): All parts of the cherry laurel plant are poisonous, particularly the seeds and leaves. It contains cyanogenic glycosides, which release deadly hydrogen cyanide (prussic acid) when chewed and digested. Just a small number of chewed fruits can be fatal to a child, with reports suggesting as few as ten can be lethal. Adults require a larger dose, but the risk remains significant.
Mountain Laurel (Kalmia latifolia): All parts of this broadleaf evergreen are poisonous to humans and animals. It contains grayanotoxins, potent neurotoxins that interfere with normal skeletal and nerve function and hinder heart muscle action. In fact, even the honey made from bees feeding exclusively on Mountain Laurel nectar can be toxic, a condition known as 'Mad Honey' disease. Ingesting just a few leaves can cause severe symptoms.
Portuguese Laurel (Prunus lusitanica): Contains similar cyanide-releasing compounds to the Cherry Laurel, although often in lower concentrations. The dark, tempting berries are particularly dangerous to humans and pets if ingested.
The Exception: Bay Laurel (Laurus nobilis)
Culinary bay leaves come from the Bay Laurel tree, which is a different species entirely. Its leaves are edible and used for flavouring, though the berries are considered mildly toxic. As a general rule, it is important to be absolutely certain of the plant's identity before using it in food. Never consume the raw leaves or berries of any laurel unless confirmed to be the true Bay Laurel and properly prepared.
Comparison of Common Laurel Varieties
| Feature | Cherry Laurel | Mountain Laurel | Portuguese Laurel | Bay Laurel (Culinary) |
|---|---|---|---|---|
| Toxicity Level | Highly Toxic (Cyanide) | Highly Toxic (Grayanotoxin) | Moderately Toxic (Cyanide) | Not Toxic (Leaves Only) |
| Toxic Parts | All parts, especially leaves & seeds | All parts, including honey | Berries and leaves | Berries mildly toxic, leaves are not |
| Primary Toxin | Cyanogenic Glycosides | Grayanotoxins | Cyanogenic Glycosides | Mildly toxic seeds |
| Common Use | Landscaping, hedges | Ornamental shrub | Landscaping, hedges | Culinary herb |
| Risk to Humans | High, especially children | High, affects heart/nerves | Moderate | Low (with proper identification) |
Symptoms of Laurel Poisoning
Symptoms vary depending on the specific laurel species, the amount ingested, and the individual's body weight, with children being at significantly higher risk.
- Gastrointestinal Distress: Nausea, vomiting, abdominal pain, and diarrhea are common initial signs.
- Cardiovascular Issues: Both rapid heart rate (tachycardia) and a dangerously slow heart rate (bradycardia) can occur with Mountain Laurel poisoning.
- Neurological Effects: Dizziness, headache, seizures, convulsions, muscle weakness, and tremors can manifest.
- Respiratory Problems: Decreased or difficulty breathing, potentially leading to respiratory failure.
- Other Severe Effects: In severe cases, poisoning can lead to coma or death. 'Mad Honey' poisoning from Mountain Laurel nectar can also cause severe hypotension (low blood pressure).
What to Do in Case of Suspected Poisoning
If you suspect that a person, particularly a child, has ingested any part of a toxic laurel plant, immediate action is necessary. Do not wait for symptoms to appear.
- Contact Emergency Services: Immediately call emergency medical services or your local poison control centre.
- Gather Information: Be prepared to describe the plant, the part that was ingested, and the approximate amount. If possible, bring a sample of the plant with you to the hospital for proper identification.
- Follow Professional Advice: Do not induce vomiting unless specifically instructed by a medical professional or poison control.
- Administer Activated Charcoal: A doctor may administer activated charcoal to help absorb the toxins in the stomach.
- Supportive Care: Treatment often involves supportive care, such as monitoring vital signs, administering IV fluids to prevent dehydration, and managing specific symptoms. In severe cases of cyanide poisoning, an antidote might be necessary.
Prevention and Safety Measures
- Educate Yourself: Learn to identify the different laurel species in your garden. The glossy, deep green leaves of Cherry Laurel are a common sight, while the culinary Bay Laurel has more aromatic, lanceolate leaves.
- Keep Children and Pets Away: Plant toxic laurels in areas inaccessible to children and pets, or use barriers like fencing.
- Safe Handling: Wear gloves and long sleeves when pruning or handling toxic laurel varieties, as some individuals may experience skin irritation. Dispose of clippings responsibly; do not burn them, as this can release toxic fumes.
- Never Taste Unknown Plants: Teach children never to eat any part of a plant they find outdoors without a trusted adult's permission.
Conclusion
While the culinary Bay Laurel is a safe and common household herb, the majority of garden laurels, including Cherry and Mountain laurel, are highly poisonous to humans and pets due to the presence of potent toxins like cyanide and grayanotoxins. The exact amount needed to cause poisoning is highly variable and depends on factors like the species, plant part, and the individual's body size. For young children, even a small quantity of berries or leaves can be life-threatening. It is therefore essential to exercise extreme caution, ensure proper plant identification, and keep toxic varieties out of reach of vulnerable individuals. In any case of suspected ingestion, immediate medical attention is a necessity.
Resources
For more information on poisonous plants, including identification and safety tips, you can consult authoritative sources like university agricultural extension services.(https://plantaddicts.com/are-mountain-laurel-poisonous/)
