Oak (Quercus robur):
Oak, the remedy for those who are normally strong and brave in character but find their strength beginning to wane, is made by the sun method.
Oak wood has been used in building, furniture-making, to provide charcoal to smelt precious metals and in shipbuilding. Admiral Nelson’s ship HMS Victory was built using an estimated 5,000 oak trees. When the Armada came to England in 1588, King Philip of Spain ordered that the Forest of Dean in Gloucestershire be burned down to destroy the oak trees, to prevent any more shipbuilding. Oak’s attraction to shipbuilders was partly due to the tree’s status in mythology. Connected to the gods Thor and Zeus, it was believed to be a fire and lightening charm and to possess magical as well as intrinsic strength.
British king Charles II was said to have sheltered in an oak tree at Boscobel House after the Battle of Worcester in 1651, to escape his Parliamentary enemies. In 1660, the date Charles was returned to the throne (29th May) became a public holiday, which was observed as Royal Oak Day and was celebrated until 1859. On this date, churches, houses and people wore oak and today it is still celebrated as Founder’s Day at the Royal Chelsea Hospital, which was founded by Charles II in 1681.
The mythical strength of oak translated into some of its traditional uses. Toothache sufferers sometimes hammered a nail into an oak tree, believing the tree would take away their pain! ‘Lungs of oak’ were taken by people with tuberculosis or chest complaints – this was actually a lichen, Stricta pulmonaria, which resembled lungs and grew on some types of oak tree. Couples were often married under oak trees, hoping to absorb the tree’s strength and vitality and the bark of oak trees was used to make love potions.
Oak bark contains tannins but these are more abundant in the galls. Galls form when oak bark wasps lay their eggs on the branches. When the larvae hatch and begin to feed on the tree, they excrete a substance which irritates the tree and it responds by producing a gall – an abnormal outgrowth of tissue. The gall provides food and protection to the larvae which exit the gall when they become wasps. Oak galls are used to produce iron gall ink, which was the most important writing material in the West from the Middle Ages to the 20th century. Aleppo galls from Quercus infectoria, Aleppo oak, contain the greatest amount of gallotannic acid (over 50%) while galls from the common oak contain about 20%.
Gallotannic acid from the gall is mixed with water to produce gallic acid which is then reacted with vitriol (iron(II) sulphate) to produce the ink. Gum arabic, from acacia trees, is added as a suspension agent. The ink is soluble (as Fe2+) and light-coloured but darkens and becomes insoluble by oxidation when it is absorbed by the writing surface, making it permanent.
Iron gall ink was used in the Dead Sea Scrolls, to draft the US constitution, by Rembrandt and van Gogh to draw with and by J.S. Bach to compose. Although not widely used today, the use of permanent blue-black iron gall ink (Registrars’ Ink) is a requirement in the UK for legal documents such as birth, marriage and death certificates, in ships’ logbooks and in clergy rolls.
The tree’s seeds, or acorns, were a traditional food for pigs and historically were eaten by peasants in times of famine. Oak bark was used to produce a brown dye and the tannins were used to tan leather. The name of the light brown colour tan or tawny come from the Latin tannum for oak bark.
Medicinally, the bark is used as an astringent e.g. for those suffering from diarrhoea, dysentery or haemorrhoids. A decoction is used as a gargle for tonsillitis or laryngitis. Oak galls have the same effects and provide the strongest of all vegetable astringents.