Poisonous plants

What is a poisonous plant?

Quite simply - this is the wrong question to ask. A better question is "how poisonous is this plant?". For anything, even water, is poisonous if taken in excess!

So wild cabbage is known to be poisonous to some animals. Yet humans have long cultivated cabbage as a basic food plant. So the question is "How much cabbage would you have to eat to suffer harm?"

There is a measure of poisonous potential - the LD50. This is the dose that will kill half of the animals it is administered to. Unfortunately you are unlikely to find any such measurement quoted for "poisonous plants".

Anyone interested in wild food plants should familiarise themselves with the commoner dangerous plants: there are relatively few! Wikipedia has an interesting list of poisonous plants, but most of these the average forager will never meet as the list is world-wide. Many however are common garden plants. A Google for poisonous plants will reveal much of interest.

As a wild food forager it is useful to taste small samples of new or unknown plants. There are extremely few plants where this habit is dangerous! Most of the dangerous ones are plants that have toxic sap, where contact can cause blistering. Once you know a litle about these, taste testing is not particularly dangrous - most of the poisonous plants are likely to taste horrible! Plant toxins have evolved to stop browsing by animals and our taste buds started evolving to tell us what not to eat!

Animal poisons

Many human foods are toxic to animals. So Onions are particularly toxic to cats - but try getting your cat to eat any!

And many plants that are toxic to humans can be eaten by some animals. So Acorns in sufficient quantity can harm you, yet pigs eat them with impunity!


There are several books on poisonous plants. For instance "Poisonous Plants and Fungi" by Pamela North. This lists several plants that are used as food by humans: All of these are food plants grist to the wild food forager's mill. Yet the wild food gatherer is unlikely to eat any in large quantities. Maybe if we ate huge quantities our health might suffer!

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Page first published Friday the 7th of August, 2015.
Last modified: Sat, 25 Nov 2017 12:58:24 GMT
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