Plant of the Month November 2017

 The oak trees and oak galls.

There are over 250 different varieties and cultivars of the oak tree. At Reveley we have a large common oak tree (Quercus rubur) dominating the North side of the Sunclock lawn. This is a fine specimen, and we also have another less common younger red oak (Quercus rubra) on the South-east of the same lawn. As it’s name suggests it has much darker red/brown leaves.

a mast year

This autumn there has been an enormous crop of acorns on the common oak after a number of less fruitful years.Indeed throughout the country trees of many species have seeded and fruited this season to an unusual extent. It is known as a ‘mast year’. The word comes from an old English word meaning nuts accumulating on the ground, especially those used for fattening pigs. This event occurs every few years and is most certainly weather related, with the tree flowers being pollinated in mild weather conditions – thus producing an exceptional crop of acorns, chestnuts, apples and other seeds.

Oaks are well known for their exceptionally strong timber, but in these days it is largely forgotten that they once were a prime requisite for ink. The small brown oak apples or ‘galls’, which have also been prolific this year are a source of gallic acid. Galls are formed by chemical irritation from very small wasps who lay their eggs on the terminal branches of oaks. The oak apples grow and protect the developing larvae inside until they eventually emerge and fly off.

Historically galls were ground up and mixed with ferrous sulphate and gum Arabic from acacia trees to produce the ink.

There are a few oak galls on our Reveley oak, but are they are more easily seen at eye level on the young sapling oak trees in Merry Hill fields. 

The other important historical use of gallic acid was that it was used as a critical chemical by the photographic pioneer William Henry Fox Talbot to develop the images in his invention of the Calotype process in 1841. 

 Previous Months

October 2017

September 2017

August 2017

July 2017

June 2017

May 2017

April 2017

March 2017

February 2017

January 2017

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