Californian Buckeye, California Horsechestnut

Aesculus californica

Physical Characteristics

Aesculus californica is a deciduous Tree growing to 12 m (39ft) by 10 m (32ft) at a medium rate. See above for USDA hardiness. It is hardy to UK zone 7 and is not frost tender. It is in flower from July to August, and the seeds ripen in September. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers dry or moist soil.

Distribution

South-western N. America - California.

Habitats

Woodland Garden Canopy; Secondary;

Edible Uses

Edible Parts: Seed Edible Uses: Seed - cooked[22, 46, 63, 92, 94, 95]. It can be dried, ground into a powder and used as a gruel[2]. The seed contains about 23% protein and has an agreeable taste[213]. The seed is large, and can be up to 5cm in diameter[82]. It is often produced abundantly in the warmer areas of Britain and is easily harvested[K]. This was the most commonly used Aesculus species in N. America[213]. It does, however, contain poisonous saponins (see the notes above on toxicity) and so needs careful preparation before being eaten. The seed needs to be leached of these toxins before it becomes safe to eat - the Indians 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[213]. Most of the minerals etc would also have been leached out by this treatment[K].

Medicinal Uses

Expectorant Odontalgic Salve The seed contains saponins and can be used as an expectorant[94]. The crushed fruit is applied as a salve on haemorrhoids[257]. A decoction of the bark is used in the treatment of toothache and loose teeth[257].

Known Hazards

The seed is rich in saponins. Although poisonous, saponins are poorly absorbed by the human body and so most pass through without harm. Saponins are quite bitter and can be found in many common foods such as some beans. They can be removed by carefully leaching the seed or flour 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 food that contain saponins. Saponins are much more toxic to some 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[K]. The flowers of this plant are toxic to bees[94].