Acorns make a great subject for watercolour painting because they show such a wide range of colours, from bright yellow to deep brown. The large oak tree in our garden produces many acorns, and sometimes they grow with unusual attachments. In the sketch below, you can see an example of one of these curious structures.
These unusual structures are quite challenging to draw, but I’ve tried to show them from two different angles. After doing some research online, I found out what they are: a small wasp called the Knopper gall. You can find explanations in both Dutch and English at: http://www.bladmineerders.nl
The gall looks as if several small leaves have been stuck together, with a hole at the end where the young wasp can emerge. Its life cycle is quite complex, but you can read more about it on the website.
