That Old Chestnut…

Most people are familiar with the chestnut tree, having learned to identify it as children from the spiky cases and glossy conkers which fall in the Autumn. Horse chestnut is an invaluable medicine in any modern herbal dispensary, but the extract used by herbalists isn’t derived from the same nuts that decorate our tables at Christmas. So what’s the difference?

Horse Chestnut as Herbal Medicine

The horse chestnut tree (Aesculus hippocastanum) is not native to the UK, but was originally imported from Asia as an ornamental feature for wealthy folk’s gardens. It can live up to 300 years, and is a welcome refuge for many birds, insects and other animals in the cold, winter months. The name is thought to refer to its ability to heal horses and cattle of respiratory illnesses, or may be in reference to the small horseshoe-like markings that are present on the branches of the tree.

The tree has a long history of use by herbalists for the treatment of conditions usually related to venous insufficiency. It has very strong astringent properties, making it helpful in cases where things need “tightening up.” It makes a soothing salve for the treatment of piles, varicose veins or prolapsed discs, and is also a useful first aid remedy for cuts and grazes. I even know of a colleague who swears by its use in her anti-cellulite cream. Boiling the fruits in water makes a strong decoction which can be used as a mist to soothe and calm cases of acne where the pimples are hot, red, hard and sore.

Although horse chestnut is a valuable medicine, it is extremely toxic and should only ever be used under careful supervision by an experienced practitioner. It contains saponins (bitter-tasting, organic chemicals that have a foamy quality when agitated in water,) which can make you very sick if taken in large doses. Applied topically or measured in drop doses for short acute episodes, it’s usually combined with other appropriately selected herbs to create a balanced formula tailored specifically to the individual.


The Difference Between Horse Chestnuts and Sweet Chestnuts

The horse chestnut used in herbal medicine comes from the Aesculus genus. These trees produce toxic, inedible nuts and should not be confused with the edible variety (Castanea sativa.) It is possible to tell the difference by their cupules (isn’t that a satisfying word!) which is the technical term for the spiky nut casing, as well as the shape of the nuts themselves.

The photographs below illustrate the difference.




On the left: The fleshy, bumpy husk of the horse chestnut. The nuts are rounded and smooth, with no tassle or point on the end.

On the right – The edible sweet chestnut has a ferociously spiky husk which often requires gloves to handle! Unlike the inedible horse chestnuts, sweet chestnuts have a distinctive pointed tassel on the tip.


Sweet chestnuts are usually much smaller and found in clusters. The leaves of the tree can also help to distinguish one from the other. The sweet chestnut tree has single, long, serrated leaves, while the horse chestnut has hand-shaped leaves with deeply divided lobes or ‘fingers’.


Edible Sweet Chestnuts

Sweet chestnuts (the kind we eat at Christmas) come from Castenea sativa. They contain high levels of vitamin C and are much lower in fat than other nuts. They contain twice as much starch as a potato, earning it the nickname of “bread tree” in some regions of the world. Roasted chestnuts are popular in Italy. They have a slightly sweet flavour, with a soft texture not dissimilar to sweet potato. No special equipment is necessary to roast them in your oven. A detailed explanation of the process can be found here if you want to have a go:

How To Roast Sweet Chestnuts in the Oven

As with all fresh produce, you should check for quality before buying from a store. A ripe chestnut will have a slight give when squeezed, indicating it’s been properly cured. A chestnut shell with too much give indicates it’s past its best and has become dehydrated. Some chestnuts can even contain weevil larvae. For this reason it’s common practice among growers to soak the nuts for 20 minutes in water at 120F to kill any parasites which may be lurking in the produce.


A note of caution:

Gathering wild food and medicines is not without its perils. This blog is intended to point out how important it is to ALWAYS be sure to have positively identified anything you are picking or harvesting. Consuming horse chestnuts instead of sweet chestnuts is an error you wouldn’t want to make!

I can’t stress highly enough that you should NEVER eat ANY wild plant unless you are 150% certain of its identification.

Interested in learning more about the wild foods and medicines in your area? I’ll be hosting a number of wild medicine walks in and around Cornwall from March 2022. Details of upcoming walks are posted in the newsletter, and also shared on my Instagram feed. Seasonal foraging eBooks are also being (slowly) added to the the website shop.


Resources and further reading:

Further information about foraging for wild plants can be found on the following excellent websites:


Recommended reading:

The Forager’s Calendar by John Wright














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