Poisonous plants you should know about

All these plants grow in Europe, so in theory you may come across some of them here in Portugal. Forewarned is forearmed so they say. Some are more toxic than others, and some toxins are faster acting than others. Some toxins have an effect when ingested, while others are by skin contact.

Below are a few to get you started with your knowledge of toxic plants. All are common and widespread, with some resembling edible species, so you would be wise to double-check.

Oleander is a very common plant here with all parts being toxic, and is popular as being hardy and heat tolerant, and will flower at a time when little else can stand the heat. My husband found out the hard way, by accidentally getting the sap on his arms – and it caused the most unpleasant itching/burning sensation that lasted for days. Just touching the plant and tree sap with bare hands or inhaling the smoke of burning oleander can induce toxic effects, so snacking on leaves or flowers would be a definite no-no.

Brugmansia, commonly known as Angel Trumpets, has attractive pendulous trumpet-shaped flowers, but all parts of all varieties are poisonous. They are toxic to both people and animals, so be careful that your pets don’t try them either. Furthermore, the smell of its flowers can cause skin irritation, headaches or even nausea in sensitive people. The intense psychoactive compounds derived from Brugmansia do have medical uses but be warned - inhaling, touching, and eating any part of an angel's trumpet can have several unpleasant side effects and may result in death in severe poisoning cases.

Castor oil plants are very striking, with bristly-spined bronze-to-red clusters of fruits that are attractive but are often removed before they mature and are most often grown as an ornamental plant. Castor oil plants are best known for the oil extracted from their seeds (anybody remember getting a spoonful to aid, um, bathroom movement?) and the poison part is eradicated during the cooking and refining process. But ‘don’t try this at home’ as they say, as the remaining plant is still very lethal.

Foxglove -Digitalis purpurea, has a typically purple flower, and all parts of these plants contain powerful toxic alkaloids that act on the heart. Some have used the plants' leaves as toilet paper when ‘caught short’ in the wild, but this is not to be generally recommended as skin reactions have been reported (where you least want them!).

Hemlock, Conium maculatum – this species is native to many countries, including Portugal. The flowers of hemlock are an umbrella-shaped cluster of tiny white blooms on a relatively robust stem, which is round and hollow. The leaves are somewhat finer and frillier than cow parsley but the differences are subtle, and some people say hemlock has an unpleasant smell. It has been deliberately grown as a medicinal herb in the past even though it is highly poisonous, and is on the Portuguese List of Dangerous Species with a Category A1 – not to be handled without due precautions.

What is sap and are all dangerous?

Sap is that sticky substance you sometimes see oozing out of plants and trees, and is a food for the plant - think of it as their life-blood.

The sap from some plants, such as some aloes and the agaves are very acidic and can cause allergic reactions, so be cautious. Even the Opium Poppy, Papaver somniferum - both the cultivated and wild kind - have saps that are dangerous, but the dried seeds are safe and are used in breadmaking.

But one tree sap is definitely edible - pure maple syrup is the most well-known product made from tree sap — and it's delicious (hello, pancakes and waffles).

Do not be afraid

This is not a conclusive list and shouldn’t make you afraid of plants – they aren’t like Triffids lying in wait to grab you! Most plants have developed toxins to defend themselves from insect pests and other predators, so just be aware of what is dangerous out there before handling or snacking on something new.

Marilyn writes regularly for The Portugal News, and has lived in the Algarve for some years. A dog-lover, she has lived in Ireland, UK, Bermuda and the Isle of Man. 

Marilyn Sheridan