Common Name: Red Horse Chestnut

General Information

Aesculus × carnea is a deciduous tree with a rounded crown; it can grow 9 - 25 metres tall[].
The plant is often grown as an ornamental in parks and large gardens and is sometimes harvested for medicinal purposes and as a source of saponins.

Known Hazards

Most, if not all, species in this genus are poisonous, containing the glycoside aesculin, the saponin aescin, and possibly alkaloids[].
The seed is rich in saponins[].
Although poisonous, saponins also have a range of medicinal applications and many saponin-rich plants are used in herbalism (particularly as emetics, expectorants and febrifuges) or as sources of raw materials for the pharmaceutical industry. Saponins are also found in a number of common foods, such as many beans.
Saponins have a quite bitter flavour and are in general poorly absorbed by the human body, so most pass through without harm. They can be removed by carefully leaching in running water. Thorough cooking, and perhaps changing the cooking water once, will also normally remove most of them. However, it is not advisable to eat large quantities of raw foods that contain saponins.
Saponins are much more toxic to many cold-blooded creatures, such as fish, and hunting tribes have traditionally put large quantities of them in streams, lakes etc in order to stupefy or kill the fish and make them easy to catch[].

Botanical References

,

Range

A cultivated hybrid of garden origin, Aesculus hippocastanum x Aesculus pavia.

Habitat

Not known in the wild.

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Deciduous Tree
Height	25.00 m
Pollinators	Bees
Cultivation Status	Ornamental

Cultivation Details

Aesculus × carnea prefers a continental climate with its hot summers, cold winters and usually a clear movement from one season to another. The dormant tree can tolerate temperatures down to at least -15°c, but in more maritime climates it is often tempted to come into growth early and this new growth can easily be damaged by late spring frosts[].
Prefers a deep loamy well-drained soil but is not too fussy[, ].
There are some named forms selected for their ornamental value[, ].
Seedlings quickly develop a taproot and larger plants can be difficult to transplant[].
Abnormal cell development in this species may result in eruptions on trunks over 30cm in diameter - these ultimately decay[].
Although a hybrid species, it breeds true from seed due to a doubling of the chromosomes[, ].

Edible Uses

We have no information for this species, but the following notes almost certainly apply to it.

Seed - cooked. It can be dried, ground into a flour and used as a gruel. The seed is quite large, about 20mm in diameter, and is also easily harvested. Unfortunately, it is rich in saponins and these toxins need to be removed before the seed can be eaten. See also the notes above on toxicity.

The following notes apply to Aesculus californica, but are probably also relevant here:-
The seed needs to be leached of toxins before it becomes safe to eat - the native Americans would do this by slow-roasting the nuts (which would have rendered the saponins harmless) and then cutting them into thin slices, putting them into a cloth bag and rinsing them in a stream for 2 - 5 days[]. Most of the minerals etc would also have been leached out by this treatment[].

Medicinal

The plant is used in Bach flower remedies - the keywords for prescribing it are 'Excessive fear' and 'Anxiety for others'[].

Other Uses

Saponins in the seed are a soap substitute[]. The saponins can be easily obtained by chopping the seed into small pieces and infusing them in hot water. This water can then be used for washing the body, clothes etc. Its main drawback is a lingering odour of horse chestnuts[].

Propagation

Seed - best sown outdoors or in a cold frame as soon as it is ripe[, ]. The seed germinates almost immediately and must be given protection from severe weather[]. Seedlings develop a large taproot following germination and so, if grown in containers, should be given sufficient root room[]. The seed has a very limited viability and must not be allowed to dry out. Stored seed should be soaked for 24 hours prior to sowing and even after this may still not be viable[, ]. It is best to sow the seed with its 'scar' downwards[]. If sowing the seed in a cold frame, pot up the seedlings in early spring and plant them out into their permanent positions in the summer. This species is a garden hybrid though it breeds relatively true from seed[].