Common name: Ring-cupped oak, Japanese blue oak
The leaves of Quercus glauca are grey-green on the underside, and its acorns have several rings around the cup. It is native to Asia. Unlike many other oaks, it is evergreen.
Garden photos by Tresa Horney.
Acorn photo: KENPEI / CC BY-SA (http://creativecommons.org/licenses/by-sa/3.0/)