knopper gall

gall, early August (photo Hans Jonkman)

same gall, pulled out of the cupula

the “stalk” of the gall has pushed itself between cupula and acorn

The gall is attached to the cupula, next to the attachment of the acorn

The gall chamber, still quite small, is located in the “stalk”

Another specimen, autumn aspect; the gall chamber has grown proportionally

The acorn has been overgrown and is aborted.