Acorn cup – Quercus sp.
Miocene
Succor Creek Flora
Rockville
Oregon, USA.

The genus Quercus represents the oaks, a long lived and ecologically important group of flowering plants that were already well established by the Miocene. The acorn cup (cupule) is the woody structure that partially encloses and supports the developing acorn, and it is often one of the more robust parts preserved in the fossil record.
20mm acorn cup on 95mm slab