Human uses
Trees are not just beautiful to look at: for centuries, humans have made use of their remarkable properties to heal themselves, feed themselves, wash themselves and even… curb their urges!
The Chinese Goldenrain Tree (Koelreuteria paniculata) – native to China and Korea – owes its common name to the saponin found in its bark and fruit — a naturally foaming substance once used as soap. Its leaves turn yellow or orange in autumn. Its upright flowers, arranged in yellow clusters 30 to 40 cm long, develop into small green then brown capsule-shaped fruits, each containing three black seeds. Today, the drought and pollution resistance of this tree, which grows to a maximum height of 15 metres, makes it a valuable asset for urban planting schemes. Used in dyeing, the soapberry tree produces a dark blue colour from its leaves and a yellow from its flowers.
The Chaste tree (Vitex agnus-castus) – native to the Mediterranean region – is a shrub with a history that is surprising to say the least! Its nickname — ‘monks’ pepper’ — sums up its main use in the Middle Ages: its berries, consumed by certain members of the clergy, were reputed to calm sexual urges and help them observe their vow of chastity. Its Latin name, which literally means ‘chaste lamb’, speaks volumes about this reputation! Its berries were also used as a substitute for pepper and still play a recognised role today in regulating female hormones.
The horse chestnut (Aesculus hippocastanum) – native to the Balkans – is one of the most familiar trees on our walks. European botanists first discovered horse chestnut seeds in the 16th century in Constantinople (now Istanbul). They assumed that this previously unknown tree could only have come from the mythical lands of India, as was the case with most of the goods available in that city at the time. This species was therefore mistakenly named the horse chestnut, as it is in fact native to the mountains of Albania and northern Greece (European botanists did not discover this until half a century later).
This species was the first to be planted extensively in the squares and streets of European cities from the 16th century onwards. At that time, the appearance of public spaces in city centres was very stark and austere, and most residents, who came from the countryside, were rather in search of nature.
Widely planted for its generous shade, its beautiful clusters of white flowers in spring and its resilience to pollution, its Latin name, Hippocastanum, means ‘horse chestnut’: its nuts were used in veterinary medicine to treat coughs in horses. Today, they are found in pharmacies in preparations designed to improve blood circulation. The saponin present in the nuts helps keep moths out of wardrobes.
Did you know? The hard, shiny black seeds of the Chinese soapberry tree were traditionally used to make necklaces and rosaries. In China, it was planted near graves so that its yellow flowers would cover the graves with a shower of golden petals – hence its nickname, the ‘golden rain tree’.
In Geneva, an official chestnut tree heralds the arrival of spring every year. Its first bud is closely watched by the locals — and even by journalists! And if you’re looking for a natural good luck charm, tradition has it that a chestnut slipped into your pocket wards off bad vibes.
