This species has been confused in China with Aesculus chinensis, but it differs in several characters, including its sessile (vs. petiolulate) leaflets, crenulate (vs. serrulate) leaflet margin, conic or cylindric-conic (vs. cylindric) thyrse, and verrucose (vs. dotted but smooth) capsule[].

Common Name: Japanese Horse Chestnut

General Information

Aesculus turbinata is a deciduous tree that can grow up to 30 metres tall. The bole can be up to 200cm in diameter[].
He tree is harvested from the wild for local use as a food and source of materials. It is cultivated as a timber crop and is also grown as an ornamental in parks and large gardens[].

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

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Range

E. Asia - Japan

Habitat

Mountains, especially in ravines, all over Japan[]. In deciduous forests, especially in moist slopes along streams[].

Properties

Edibility Rating
Other Uses Rating
Habit	Deciduous Tree
Height	20.00 m
Pollinators	Bees
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Aesculus turbinata is said to prefer a continental climate with its hot summers, cold winters and usually a clear movement from one season to another. The dormant plant is very cold tolerant, 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[, ].
Seedlings quickly develop a taproot and larger plants can be difficult to transplant[].

Edible Uses

Young leaves cooked[]. Some caution is advised on this entry since the leaves are likely to contain toxic substances (see notes above on toxicity).

Seed - cooked. It can be dried, ground into a flour and used as a gruel. The starch is extracted and eaten[]. The seed is quite large, about 25 - 30mm in diameter, and is easily harvested. Unfortunately it is also rich in saponins and these 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 North 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

None known

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[].

Wood - weak, nicely grained. Used for house fittings, domestic items etc[].

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.