Category Archives: Poisonous herbs


A few photos and short comments today as we rapidly approach Beltane, the festival of early summer.

Lime trees – Tilia – Linden in Amsterdam

This week, the Lime trees which line many Amsterdam streets, burst into leaf. I love to eat these leaves, they have a mild flavour, are not tough and they bring many nutritional and medicinal uses. The trees in this street show a characteristic of Lime, they often grow leaves down the trunk. This is a bonus for foragers as it makes the leaves easy to harvest from a tree species which can easily reach 20 meters.

Symphytum x uplandicum in flower

Comfrey plants are in bloom. This helps up to identify the species and help discern whether the comfrey growing near you in the white flowering Symphytum officinale, which is not seen as safe in internal preparations (such as teas) but helpful in external preparations (such as skin salves) or Symphytum uplandicum, which tends to have leafy parts which don’t contain the hepatotoxins in it’s leaves and flowers.

Another Symphytum in flower – 20 m away from the purple one above

Next up, Hawthorn. This is called by many names around the world, including May Tree because it generally bursts into bloom around the first of May. Well this year, it is a little earlier than I have seen for a while. It has been in bloom for over a week and it looks very pretty. Hawthorn is a tree wrapped in much folklore and superstition, due to the plethora of medicinal uses associated with it. This is one of my favourite city herbs.

Hawthorn in bloom. Crataegeus monogyna.

I have been Zooming with some of my apprentices over the past few weeks. I am posting the date and time on the Apprenticeship events page and any who fancy joining me for a chat, do. One week, there was a question about creams so I made them a video about it and have actually been more in love with the cream recipe since! It is a real skin soother. I made this one with orange blossom water and olive oil.

My Zoom cream. Orange blossom water and olive oil.

Magnolia is going over now, the flowers that it. If you have uses for the leaves then now is the time to harvest a few of those! Here is a beautiful specimen which grows in my local cemetery which happens to also be the Netherlands national arboretum – A nice double function, you may agree. The cemetery also houses the national funeral museum. An incredibly interesting place.

Yellow petaled Magnolia in Neiuwe Osster Begraafplaats, Amsterdam Oost.

Below is a photo of an invasive weed which grows in parts of Park Frankendael. I identified it several years ago as Pennsylvania pellitory (Parietaria pensylvanica), a non-stinging member of the nettle family and a sister of the well known traditional herb, Pellitory-of-the-wall (Parietaria officinalis). It is called Glaskruid in Dutch and Cucumber weed in parts of the USA. Both helpful common names as it kind of looks glassy when held to the light (translucent) and it has a mild cucumer taste. Sadly, it is also known as asthma weed because when the flowers start to release their pollen, it can cause havoc for people with respiratory issues. This prime specimen is growing in the woodland area of the park. There is a single mature plant growing in the River of Herbs nettle orchard, on the left hand side, soon after entering through the gate. We are leaving it there and will keep an eye on it when the weedy seed spreading time comes.

Pennsylvania pellitory

Next today, can you see the Elderflower (Sambucus nigra) in the photo below? I found this yesterday, on my walk back home from the supermarket in Oostpoort. Beautiful, fragrant (often nastily fragrant), edible, medicinal and fabulous Elderflower!! I just thought you may like to see it as this heralds the start of the main foraging season for many people. Here are a few recipes and thoughts about elderflower. As you will see from those posts, I am a big fan of them and each year, as well as making foods, drinks and home remedies from them, I dry a batch or two and store carefully to use as a tea during times when my immune system needs a boost. Elderflower tea is a well known traditional remedy for. Since COVID-19 hit Amsterdam, my Elderflower tea has been drunk at least once a day so my stock has steadily been depleted. It will certainly be restocked in a few weeks time, when the flowers are open everywhere and I can harvest some for drying.

I am trying to grow more vegetables than usual at home. I may write a post about these later but for now, here’s a windowsill shot of some veg scraps which I am trying to bring on. The Paksoi is particularly fast!

Romaine lettuce base, basil cuttings, paksoi base, spring onions, some sprouting lentils, celery base and carrot tops. Day 1.

You may have read about my Rosemary beetle problem. I can now report that the issue is improved but continuing. Yesterday, I picked only 5 beetles from the pruned bush. My poor Rosemary bush!

Rosemary beetle – Photo credit:  Secret garden

Lastly, a mention of a Dutch woman who asked for my advice by telephone earlier this week. She had been foraging in an Amsterdam park and noticed a young fern head had been snapped off and removed in an area with many fern heads were coming up. She took this to mean that some knowledgeable forager had found an edible fern and harvested some. She has heard that some young fern heads are edible and she wanted to try so she snapped one off, took it home, prepared and ate it. Unfortunately although now recovered, she became quite ill and she wondered what to do and did I know much about ferns.

My advice was to call her doctor or the emergency services if this sort of thing ever happened again and that if she relapsed at all now, to contact them straight away, showing them a photo of what she had eaten. Also not to follow supposed “leads” from other foragers. That fern head may have been snapped off by any number of things, from kids playing near them, a strong bird animal pecking around, a dog etc. This is just one of the reasons why I teacher foragers to pluck really gently and to leave no trace. When one person sees you have been there, others often think that it is fine to copy. Sometimes with catastrophic effects.

I don’t forage ferns and I keep a few bottles of Norit activated charcoal tablets handy, they may sometimes be helpful at absorbing toxins but hospital is your best bet, if a plant poisoning situation occurs – don’t be proud if it should happen, just call 999 / 112 / 991 etc and get professional help – quickly. And only harvest what you know really well, have identified properly and only eat what you are sure is safe for you. I am looking forward to meeting the woman and us going for a herb walk together.

Gnarly apple tree – Wishing you a blooming lovely Beltane!

So that’s it from me today. I hope that you are keeping well, getting enough fresh air and are looking forward to Beltane – May Day, this coming Friday. I certainly am! If you are on the Apprenticeship course and fancy a Zoom or socially distant meeting in the plants, let me know!


May Herbs Sauce


This herb sauce was the result of today’s rainy forage in Frankendael park.


After a quick chat with the park warden who was chopping up a massive fallen tree, Livvy and I collected a little each of Ground elder (Aegopodium podograria), Wild garlic (Galium ursinum), Wild geranium (Geranium sp), Ground ivy (Glechoma hederaceae) and White deadnettle (Lamium alba).


I took those herbs (a small handful in all), chopped them, sweated them down in a pan over low heat, with a splash of water for 10 minutes, then added a little blue goats cheese and a desertspoon of sour cream. I them blended it all to a smooth sauce with a hand blender.

The result was very tasty indeed and the balcony harvest Pansies (Viola sp) also went down a treat!

On a less tasty notes: Here is patch of poisonous Lily of the Valley, growing in the park. Just notice how similar the leaves are to those of Wild garlic. The easiest way to distinguish them (apart from the flowers) is that Wild garlic smells very strongly of garlic and Lily of the Valley doesn’t.

Contaminated Marshmallow Root

Update: Government tests show the Jacob Hooy batch of Marshmallow Root (sold from September 2012 to now) contains ATROPINE. They ask that this message be spread to people who are likely to use the root, either loose, in bags, or in mixed blends from Jacob Hooy. Many people will have it on their shelves unopened and should be warned. It will be announced online and in newspapers today. Jacob Hooy have the batch numbers. Contact them if unsure of safety of batches you have. Contact below number about poisons, contact me or the link below to report any problems you may have had with the root over the past 4 months.

One of my apprentices purchased Marshmallow root (Althea officinalis, Heemstwortel) from a local herb outlet in Amsterdam this weekend and spent Saturday night in hospital, along with her boyfriend after they made a straightforward milk decoction of the root and suffered the following symptoms:

Irregular heart beat
Blurred vision
Dilated pupils
General malaise
Loss of memory
Some nausea
Lack of bodily coordination

They are now at home recovering further from a marshmallow hot chocolate that gave more than they anticipated.

After investigation it appears that they are not alone. Someone else, completely unrelated, purchased the same herb from a different shop and had the same symptoms this weekend. Marshmallow root is seen as a safe herb, apart from potentially interfering with blood sugar levels in those with diabetes, it has no history of toxicity. The batch of herb appears to be contaminated and the Dutch food safety agency is now on the case and looking for the original source, what the contaminant actually is and how it came to be in the shops.

Please, if you have any at home which you have purchased recently in the Netherlands and have not yet tested, wait with using it until the above questions have been answered. I love this herb and eat it and decoct it regularly as part of my diet. My toddler also enjoys it now and again. I know many of you also like to use it in your families in similar ways.

Here is a link to the form that can be used to contact the Dutch food safety agency directly if needed:

If you are worried about poisoning at any time, here is the number for the Dutch Poisons Helpline:

030 274 8888

They would like to know urgently if anyone else has experienced similar problems after using the root. I’ll put my marshmallow root recipes back on line when the issue is resolved.

365 Frankendael day 218

Black Nightshade (Solanum nigrum) today. The pretty tomato like fruits and white/yellow flowers, give them away at this time of year. They are toxic.


Historic uses of this annual plant include being mixed with horehound and wine for dropsy, the juice or poultice for burns, skin ulcers, pain relief and earache. The berries will certainly harm children and sometimes adults. The toxicity of the plant varies between seasons.

You’ll be able to find many Black Nightshade plants in Amsterdam pavement gardens and plant pots, at this time of year.

365 Frankendael day 201


Here are two interesting plants; Stinging nettle (Urtica dioica), edible, nutritious and a useful tonic for the body. The other feathery looking foliage belongs to Fools Parsley which could give you quite an uncomfortable digestive system if you were to eat it, perhaps mistaking it for something such a Sweet Cicely. On an Urban Herbology walk last year, I was told about a group of young Amsterdam children who had a lovely woodland walk with a guide and foraged their dinner. Unfortunately they harvested and ate Fools Parsley, mistaking it for Wild Carrot. They all ended up in the local hospital’s casualty department with dreadful stomach pains and more. Apparently all was well in the end but I’m sure they wouldn’t have wanted that.

There are so many noxious close relatives of Fools Parsley (such as Poison Hemlock, Conium maculatum) that it’s just not worth foraging anything that resembles it – unless you REALLY know what you are doing.

Apple of Peru, Shoofly plant, Nicandra physalodes


Here’s a lovely photo which Elodie sent me today of a plant which grows well in Amsterdam. Apple of Peru, Shoofly plant (Nicandra physalodes) is a member of the Nightshade family (Solanacaea) and is somewhat poisonous. It is said to be useful as an insect repellent. I saw some seed heads from this plant at the seed swap yesterday but couldn’t remember the name. The seed heads look like pretty lanterns but the tell take tomato truss like arrangement of the fruit and the kinks in the truss stem, told me instantly that it was a nightshade.

I’m not a big fan of Nightshades but they do have many uses. Not that all Nightshades are poisonous, but all contain quantities of chemicals which should be avoided in excess. Some members of the family are packed with the toxins (such as Belladonna) so just a berry or leaf would give that excess and could kill. Others have it in quantity within the green parts alone and the fruits can be eaten occasionally (such as aubergine and tomato). Others are somewhere in between (such as Bittersweet and Black nightshade). It seems that Apple of Peru is an in between nightshade, though I won’t be testing that. It looks and feels very poisonous to me but is very pretty so it’s easy to see why it has survived.

Ginkgo Harvesting in Amsterdam


For some years, each autumn, I have trudged through putrifying Ginkgo fruits, fallen amongst fossilesque golden Ginkgo leaves, on Albrecht Durerstraat in Oud Zuid, Amsterdam. It is where I work and is a street that the local council chose to line with this amazing tree herb, many moons ago.

Ginkgo biloba is a fascinating plant. Often known as the Maidenhair tree or the living fossil tree, it is incredibly resilient to damage and pollution and is well suited to the urban environment. It has been long revered by traditional Chinese and Japanese medicine and apparently has many uses, particularly for the circulatory system.  This is apparently the most adulterated herbal extract that people buy. Most people seem to take the extract to improve their circulation, for cold hands and feet for instance and to boost their memory. Be aware that there is much conflicting evidence about the effectiveness of Ginkgo for memory loss and demetia. As ever, treat all claims with caution and if trying something new, be very cautious. Here’s a summary of the current research.


This lunchtime I was joined by 5 adults and two snuggly wrapped babies, to harvest some Ginkgo nuts which have dropped onto parked cars and the pavement.  The flesh (sarcotesta) around the nuts is HIGHLY TOXIC, containing the same chemical as poison ivy. Anyone wishing to harvest, should avoid touching it.  The chemical causes a very serious skin reaction and requires prompt hospital treatment.  Likewise, because Ginkgo acts as an anticoagulant, if you are already taking drugs which act to “thin the blood”, you should avoid the herb and consult your doctor for advice, if you really think it could be of benefit to you.   If you are allergic to aspirin or nuts, this is also a herb to avoid.

Please follow the instructions in this link if you want to know how to prepare the nuts. Note the rubber gloves and photo of blistered eyes, on that website!

By removing these smelly fruits from the pavement we are sparing the local residents from some nasal pollution and are harnessing an urban resource that people in some other countries would be very envious of.


So if you want to join me and a few others on Friday at 12:35 or on Tuesday at 12:45, please come equipt with a pair of rubber gloves, a couple of sturdy plastic bags and perhaps a spoon or chopsticks, to pick up the fruit.  Much of the current harvest has already been swept into the gutter but this is still fair game for the well prepared forager! We’ll be meeting outside of the AKO newsagent, on the corner of Beethovenstraat and Gerrit van der Veenstraat (trams 24 & 5). I’ll be wearing my yellow raincoat and rubber gloves 🙂