Both Nedre and Øvre Eiker has a picture of oak leaves in their municipal coat of arms. There are not plenty of oak trees in this area, so I have wondered why the coat of arms look like they do. After some research on the Internet, I am not much wiser. The origin of the name Eiker is apparently unsure, and despite of the presence of oak leaves in the coat of arms, the name can have originated from an old variation of the word "åker" (field). Here's a closeup of an oak tree growing in Nedre Eiker!