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When I was walking through the mountains the other day I found a small and strange fruit that caught my attention and that I couldn't identify. My buddy Irene also couldn't figure out what it was at first, but after a while she came up with a hypothesis... Could it be an oak gall (Quercus faginea)?.

If you don't know what I'm talking about, you might wonder... What are galls?

Galls are protuberances that certain trees secrete after the bite of an insect or other inducing organism, such as certain bacteria, algae, viruses and fungi.

The plant tissue grows after this interaction, producing one shape or another depending on the species or organism with which it is related. The gall then serves as a nest and food for the offspring of the organism or insect.

It was previously thought that trees produced this gall full of tannins to defend themselves against the bite, but it is not so clear that this is the case. What is clear is that certain insects have become specialized in specific varieties of trees and have manipulated the genetics and physiology of the plant to use it as an extension and support of their reproductive process.

Due to the complexity of this phenomenon, there is a science that is responsible for studying it in depth: Cecidology.

Section of a gall, with the larvae growing inside.

We know that the larva has grown and emerged from the gall when we found a small perforation. From that moment on we can use this material without harming any living being.

The Oak Galls ( Quercus robur) have been traditionally used in conventional dyeing to fix dyes to the fibers, in the process known as mordenting. Furthermore, they do not transfer any extra color that modifies the colors of the fiber.

Gall of Quercus faginea and Quercus robur.

These galls were also used to generate ferrogallic ink: a dark ink highly valued in ancient times for its quality and blackness, perfect for writing with a pen. The black of this ink is produced by mixing tannins with iron, producing a reaction chemistry that darkens the liquid (we will do another article about this in depth).

The galls or cecidia contain gallic acid which has been attributed biological properties such as antioxidant, anticancer and antiviral.

The most recognizable form of galls is a 2cm-diameter almost sphere, probably the first version of marbles that children played with in the past.

You've also heard the expression in Spanish, ''tener agallas'', literally translated as to have galls. It is another way of referring to guts, balls, eggs... as a synonym for courage. It denotes an evident coexistence with the natural environment that reaches into language and is an inheritance from our rural past.

Incredible how every day we learn something new when we enter the world of natural colors.

A pleasure to share what I learn with you through this blog.

Symbiotic hugs


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