Posted on 21 November 202219 November 2022 by David Knopper gall, Barley Field oak tree A gall from a knopper wasp, one of the various types which are found on oak trees, usually towards autumn. This was on a tree on the steep northern bank of the Barley Field. Post navigationPrevious post: Heron fishing by the shore, West ParkNext post: Giant puffball, college grounds