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Common poisonous plants in Ireland

Updated: Sep 10, 2023

Giant Hogweed

Photo of Giant Hogweed growing against a wooden fence. The plant is the same height as the fence.
The hint is in the name. Giant Hogweed is really tall. It has a thick, spiky reddish stem. Here it is against a garden fence to illustrate it's height.

Giant hogweed flowers or umbels. White frothy flowers on a thick green stem
The flowers or umbels look just like the edible hogweed but are much bigger - practically the size of dinner plates. Consequently, the seeds are much bigger too on larger, thicker stalks that are spiky.

Giant Hogweed leaves in early Spring in the centre of this photo. It is surrounded by edible hogweed leaves and nettle leaves.
Large spiky leaves of Giant Hogweed in early Spring. Spot the edible hogweed right beside it? Notice the contrast? There are nettles in this photo too!

To illustrate the contrast again - edible hogweed is in the foreground of this photo and Giant hogweed is in the background in the middle of nettle leaves - it has lighter spikier leaves.

Water Hemlock

Large water hemlock plant leaves and flowers growing next to a stream.
Water Hemlock in flower - member of the carrot family. Deadly poisonous

Water hemlock has leaves that can look similar to a number of edible plants like cow parsley, water parnsnip, chervil, flat leaved parsley and alexanders.

It has umbel shaped flowers just like any of the carrot family. It has a smell like parsley or chervil.

Coming in contact with the plant - like touching it or brushing past or even bruising a leaf with your hand will not cause any serious ill effects. It contains a powerful neurotoxin and can cause death if eaten or ingested in enough quantity. It attacks the nervous system and can trigger spasmodic convulsions.

Be very careful about identification of any member of the carrot family as this plant causes more deaths than any due to mis-identification.

How to identify:

  • Water hemlock will always be found in boggy land or near a water body (river, lake, stream, pond, canal)

  • The umbels have relatively large with well-spaced flowers on thin stems

  • If comparing to cow parsley (which is very abundant in Spring and early Summer) the leaves are more rounded and the stems are thicker.

  • If in any doubt, compare to a reputable plant guide. Always bring one with you as reference if you are not sure. Unless you are 100% sure, do not take the chance of eating it.

Arum maculatum - Cuckoo's Pint - Devil's poker

Comes out of the ground just before our beloved Allium ursinum or Wild Garlic. Get familiar with this one as you don't want to mix them up!

Behold! Note the two long lobes on the lower end of the devil's poker leaf? Wild garlic does not have these

Why you need to look out for this one: It is similar to both wild garlic or Allium ursinum and is also quite similar to some types of field sorrel, especially when in it's young stages of growth.

How to identify

  • It is usually up out of the ground before the broad leaved wild garlic - in March this year. Allium ursinum did not arrive until April.

  • Notice the long lobes at the bottom of the leaf. Wild garlic will not have this.

  • Taste - sorrel will have an immediately sharp bitter flavour and garlic - well you know yourself.

  • Look out for this among the leaves if you've picked alot.

  • Devil's poker leaves will often have dark spots on the leaf, particularly as it gets older - as if it has been bruised but this is a natural, spontaneously occurring spot or stain.

The good news is, if you do make a mistake and eat it by accident, it may make you feel unwell but it won't kill you. It is not deadly poisonous.

Allium ursinum - ramsons - bear garlic or wild garlic


These are one of my favourite Spring flowers. They appear around the end of April/early May. They are not deadly poisonous but they are definitely not edible.

The issue they cause just like the Cuckoo's pint above, is that they appear at the same time as three cornered leek which is another wild onion or garlic. The shape and colour of the leaf is similar.

Bunch of Allium triquetrum leaves on forest floor. Three cornered leek or wild garlic leaves in a bunch.
Three cornered leek leaves - note ridges on leaves and lighter colour

How to distinguish from three cornered leek leaves

  • The leaves are darker in colour and glossier

  • Three cornered leek has very pronounced and angular ridge running up the back of the leaf - hence the name three-cornered. Bluebells are less ridged.

  • Three cornered leek has a white flower striped green inside. Some bluebells are white but they are rare and do not have the green stripes on the inside.

  • The leaves don't smell or taste garlicky! :-)

Yew Tree - Taxus baccata

This is a very common tree you will often find the "Irish" species in graveyards - that distinctive columnar shaped conifer-like tree. If you are foraging for pine to make some delicious drinks or snacks, always rule out whether you are picking pine or yew. Check the underside of the leaves - it will be distinctively silvery if pine. Crush the leaves and if it doesn't smell like pine, it probably isn't!

Yew contains taxol which is used for fighting cancer but in it's raw state may poison you or kill you. Don't pick and eat mushrooms growing around the yew either for the same reason. Equally, the berries which appear in Autumn look very inviting. The flesh is actually edible but the seeds also contain taxol so remember to spit them out! Or perhaps just leave them to the birds...

two branches on a brown table. One is an example of a yew branch underside. The other is a pine branch underside. You can clearly see that the pine displays a silvery colour underneath whereas the yew does not.
Comparison of the underside of yew compared to pine. The pine is on the bottom. Note the silvery underside.

Foxglove - Digitalis purpurea

Photo of Foxglove leaf cluster - can look similar to Comfrey
Digitalis or foxglove leaves

Pink bell-shaped flowers of Digitali purpurea or Foxglove with bumblebee entering one of the flowers in the cluster.
Foxglove flower - tall spike with pink wide bottomed flowers. Apears in late Spring. Photo: Elisa Way, Unsplash

The reason why this is included is that digitalis or foxglove leaves have a strong resemblance to comfrey and borage (see photo below). Comfrey is a powerful herbal plant and used for making salves, tinctures and sometimes tea. Borage similarly is often used in herbal remedies and can be added to soups and salads.

Digitalis/Foxglove is biennial so in the first year of growth, it does not go into flower, you will only see leaves so it can be hard to identify and it is possible to confuse with comfrey. Digitalis is poisonous to humans and animals - it can prove fatal if ingested in large enough quantities. It is a plant that you should be mindful of keeping away from small animals and small children.

Digitalis isn't all bad - it has a chemical that is beneficial to heart function and is synthesised by pharmaceutical companies for medicine treating heart conditions. However, in it's raw form it can prove deadly so be sure that you are properly identifying comfrey and borage before you ingest.

Comfrey leaf floret growing from the ground. Green cluster of comfrey leaves - in Autumn. Without flower.
Comfrey leaves (without flower) They are longer, larger and more pointed at the end than Digitalis. They are a perennial and flower every year with a smaller round flower to the Foxglove.

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