A Guide to plants poisonous to Humans

Many of the plants that we grow in our gardens can be potentially fatal if eaten. This may only apply to certain parts of the plant. Even plants grown to be specifically eaten such as fruit and vegetables can be dangerous if the wrong parts are eaten. For instance, the well known vegetable, the potato, has been cultivated for centuries to be eaten but, it is only the tuber that is edible. The the foliage and, in particular the fruiting seeds on top of the plant are highly poisonous. The same applies to Rhubarb. Only the stems are edible, the leaves are highly toxic and old gardeners used to concoct a very strong weedkiller from the leaves.

The plants listed below are some of the more common species that are toxic to humans. This is by no means all of the plants that are poisonous. Don't eat any plant or plant part that you do not know for sure is safe.

The following list is based on CTTC's poison plant list as published in the Tortuga Gazette 28(1): 8-10, January 1992.
The list itself was based on the University of California Irvine, Regional Poison Center list of plants that are toxic or potentially toxic to humans. They recognize 7 levels of toxicity, indicated by a number following the plant name, the levels are explained here:-.

Explanation of Toxicity Levels

1. Non-toxic: These plants are not poisonous or there is no known record of toxicity. Exposure to these plants is not expected to cause any symptoms

2. Oxalates: These plants contain irritating substances known as oxalate salts. Contact with the sap may cause burning, swelling and pain.
Treatment: Rinse mouth, and if contact with skin, wash with soap and water. Observe for problems in swallowing and breathing, and increased drooling. Also check for irritation and swelling of mouth, lips, and tongue. Get medical help immediately.

3. Minor toxicity: Ingestion may cause some minor symptoms such as rash, vomiting or diarrhea. Ingestion of small amounts may not cause any symptoms at all. Rinse mouth and dilute with fluids. Treatment: Get medical help immediately.

4. Major toxicity: Ingestions of these plants, especially in large amounts, are expected to cause serious effects to major body organs such as the liver, heart or kidneys. Treatment: Get medical help immediately..

5. Dermatitis: Exposure to juice or sap from these plants or a puncture wound from the thorns may produce a skin rash or irritation. Skin wounds from some of these plants can be extremely painful causing large blisters and burning of the skin. Treatment:
Wash skin with soap and water. Be careful not to rub it into the eyes. Get medical help immediately.

6. Possibly toxic: Information on these plants is incomplete. Ingestions of small amounts would not be expected to cause problems. Treatment: Get medical help immediately.

7. Animal toxicity: These plants are known to cause problems in animals.Treatment: Get veterinary help immediately.

© copyright 1999, P. A. Owen

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