What is chestnut?
The Wood Guide · Choosing and comparing
ComparisonHorse chestnut and sweet chestnut
Two trees with the same name that have nothing to do with each other botanically. One provides durable construction timber and edible nuts, the other neither.
- Castanea sativa vs Aesculus
- Different leaf and fruit
- Only one is edible
Sweet chestnutCastanea sativa
Horse chestnut and sweet chestnut
Two trees with the same name that have nothing to do with each other botanically. One provides durable construction timber and edible nuts, the other neither.
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The difference in brief
The confusion comes from the name and from the fruit — both bear glossy brown nuts in a spiny husk. That is where the resemblance ends.
The sweet chestnut (Castanea sativa) belongs to the family Fagaceae, together with oak and beech. It originally comes from southern Europe and Asia Minor and was brought north by the Romans. Its fruits are the chestnuts you eat roasted in winter, and its wood is one of the few European species in durability class 2.
The wild chestnut or horse chestnut (Aesculus hippocastanum) belongs to the family Sapindaceae, together with maple and lychee. It comes from the Balkans and in our part of the world is mainly an avenue and park tree. Its fruits are poisonous, and its wood is soft, not very durable and of little value.
So they are not just different species — they are in different families and different orders. That two such unrelated trees got the same name is purely down to the similar fruit.
Sweet chestnut has a simple, long leaf with a serrated edge — like a large willow leaf with teeth. Horse chestnut has a palmately compound leaf: five to seven leaflets that spread like fingers from one point. Unmistakable, even from a distance.
- Sweet chestnut
- Castanea sativa, family Fagaceae
- Horse chestnut
- Aesculus hippocastanum, family Sapindaceae
- Relationship
- none — different families
- Sweet chestnut fruits
- edible, roasted or boiled
- Horse chestnut fruits
- poisonous (aesculin)
- Sweet chestnut wood
- class 2, durable construction timber
To be honest: the confusion is not harmless. Every autumn people end up in A&E because they mistook horse chestnuts for edible chestnuts. Aesculin causes nausea, vomiting and stomach cramps. If in doubt: don't eat them.
All the differences at a glance
| Sweet chestnut | Horse chestnut | |
|---|---|---|
| Botanical | Castanea sativa | Aesculus hippocastanum |
| Family | Fagaceae (oak, beech) | Sapindaceae (maple) |
| Origin | Southern Europe, Asia Minor | The Balkans |
| Leaf | Simple, long, serrated edge | Palmately compound, 5 to 7 leaflets |
| Husk | Densely covered with long, thin spines | A few short, thick spines |
| Fruit | Usually 2 to 3 flat nuts per husk | Usually 1 round, plump nut |
| Edible | Yes, roasted or boiled | No — poisonous |
| Flowering | Long yellow catkins, June–July | Upright white or pink flower candles, May |
| Wood | Durability class 2 | Soft, not very durable |
Four ways to tell them apart
- Look at the leafSimple and long with teeth = sweet chestnut. Five to seven leaflets like fingers from one point = horse chestnut. This works throughout the growing season.
- Look at the huskDensely covered with long, thin, hedgehog-like spines = sweet. A few short, thick spines on a green ball = horse.
- Look at the nutTwo or three flat nuts with a small point = sweet. One round, plump, glossy nut = horse.
- Look at the flowersUpright white or pink "candles" in May = horse. Long, hanging yellow catkins in June–July = sweet.
Every autumn horse chestnuts are mistaken for edible chestnuts. Husk and nut together always let you tell them apart; if you can't, leave them where they are. Aesculin is not deadly but it is extremely unpleasant.
What the two woods are worth
Useful construction timber
- Durability class 2 — outdoors without treatment
- Warm light brown, looks very much like oak
- High tannin content: unattractive to fungi
- Traditionally used for posts, facades, fencing and furniture
- Lighter than oak and easier to work
Rarely used
- Soft, light and not very durable
- Pale and almost without figure
- Moves a lot and cracks when drying
- At most for toys, crates and carving
- Mainly planted for its flowers, not for its wood
The full guide to sweet chestnut wood — figures, uses and maintenance — is on sweet chestnut wood.
Frequently asked questions about horse chestnut and sweet chestnut
Can I eat horse chestnuts?
No. Horse chestnuts contain aesculin, which causes nausea, vomiting and stomach cramps. Only the fruits of the sweet chestnut (Castanea sativa) are edible.
Are horse chestnut and sweet chestnut related?
No, and that surprises most people. Sweet chestnut belongs to the Fagaceae (oak and beech), horse chestnut to the Sapindaceae (maple). They share only the name and a similar fruit.
What is the quickest way to tell which tree I'm looking at?
By the leaf. Sweet chestnut has a simple, long leaf with a serrated edge; horse chestnut has five to seven leaflets that spread like fingers from one point.
Is the wood of both usable?
Only that of the sweet chestnut, really. It reaches durability class 2 and can be used outdoors without treatment. Horse chestnut is soft, not very durable and rarely used.
The two chestnuts in perspective
One name, two families — and only one you can eat.
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Castanea sativa — Tim van de Staak, CC BY-SA 4.0 · Castanea sativa — AnRo0002, CC0 · Aesculus hippocastanum — Vikiçizer, Public domain · Photo via Wikimedia Commons: Castanea sativa — Paulo Etxeberria, CC BY-SA 3.0