Sacred trees and groves in Germanic paganism and mythology

[10] Such groves were sometimes dedicated to a particular deity: in addition to the case of Nerthus, there was a silva Herculi sacra ('wood sacred to Hercules', an interpretatio romana) near the River Weser, and the Semnones reportedly held their rituals in honor of the regnator omnium deus ('god the ruler of all').

The scholar of Germanic religion Jan de Vries noted that placenames such as Frølund (Denmark), and Ullunda, Frösvi, and Mjärdevi (Sweden), in which the name of a deity is compounded with words meaning "grove" or "wood", suggest a continuation of the same practice, but are found almost exclusively in eastern Scandinavia; however, there is a Caill Tomair recorded near Dublin, an oak forest apparently sacred to Thor.

A mouldering birch stump surrounded by animal bones, especially from brown bear and pig, was discovered under the church on Frösön in Jämtland in 1984.

Sacred trees and groves are mentioned throughout the history of the ancient Germanic people, from their earliest attestations among Roman scribes to references made by medieval Christian monks.

[20][21] English Penitential laws made in the 11th century explicitly forbid the use of a friðplott or friðgeard—a peaceful area around stones, trees or springs.

[22] There exists also a Scandinavian folk tradition of farmers making small offerings to a "warden tree", regarded as exercising a protective function over the family and land.