Sapindaceae
Aesculus hippocastanum
Horse chestnut · Conker tree
- Part used
- seedbark
- Native range
- The Balkan peninsula — a small native range, in Greece, Albania and North Macedonia
- Morphology
- A large deciduous tree to thirty-six metres with palmate leaves of five to seven leaflets, upright candles of white flowers, and spiny capsules containing glossy brown seeds.
What is in it
Evidence
One of the better-evidenced entries in this collection. A Cochrane review found horse chestnut seed extract effective for the leg pain, oedema and itching of chronic venous insufficiency, comparable in some trials to compression stockings.
Safety
The standardised extract is the medicine; the raw seed is poisonous. Conkers cause vomiting, diarrhoea and, in quantity, more serious effects, and children are poisoned by them most autumns. Aesculin is toxic and is removed in manufacturing. Injectable aescin has caused kidney injury.
Interactions: Additive with anticoagulants; May lower blood glucose
Regulatory: Standardised extract is a registered medicine in Germany. Permitted as a listed ingredient elsewhere; raw seed is not an approved ingredient.
Historical use
Introduced to western Europe in the sixteenth century as an ornamental and quickly planted everywhere. Its medicinal use for venous complaints is comparatively recent and largely German.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
Horse chestnut is the cleanest demonstration in the collection that the preparation is the medicine and the plant is only the raw material.
Standardised horse chestnut seed extract has a Cochrane review behind it for chronic venous insufficiency, with effects comparable in places to compression stockings. Getting there requires manufacturing that removes aesculin and standardises aescin content. The raw conker a child picks up in a park is poisonous, and poisonings happen every autumn.
Its family also moved: horse chestnuts had their own family, Hippocastanaceae, and molecular work folded them into Sapindaceae with the maples and lychees. It is native only to a small area of the Balkans, and there — unlike in the parks of the world where it was planted — it is assessed as Vulnerable.
Nomenclature verified against GBIF backbone taxonomy.