Of the 26 identified Q. hiholensis acorns, only one specimen has a nut emerging from the cupule, while in the others only the perianth and styles, or umbo show.

As is typical for acorns of section Quercus, the youngest specimens still have the aborted second ovule and dividing septum present near the base of the developing fruit.

[1] At the time of study, the holotype acorn, specimen UWBM 45-I, and a series of paratype specimens were preserved in the Burke Museum of Natural History and Culture, while additional examined fossils that were not part of the type series were part of the paleobotanical collections at Arizona State University.

A total of 42 specimens in chert were studied by paleobotanists Sandra Borgardt and Kathleen Pigg, with their 1999 type description being published in the American Journal of Botany.

The Museum Flow Package interbeds, designated the type locality, are dated to the middle Miocene and are approximately 15.6 million years old.