The Language of Trees

In Old Irish, the individual letters of the Ogham alphabet are called feda (trees) or fid (tree/branch) in the singular. This is not a metaphor. Each of the 20 traditional Ogham letters carries the name of a tree or plant, and these names were understood — at least in medieval Irish literary tradition — to be literal: the letter Beith is birch; Dair is oak; Saille is willow.

The question of why is one of the more interesting puzzles in Celtic scholarship.

The Tree Alphabet

Here are the 20 traditional Ogham letters with their tree associations, as recorded in medieval Irish manuscripts:

Where Do the Tree Names Come From?

The tree associations are documented in a medieval Irish text called Auraicept na nÉces (The Scholar’s Primer) and in the Book of Ballymote. These sources provide the letter names, their tree associations, and sometimes symbolic meanings.

Scholars debate whether the tree names were original to the script or were added later as a mnemonic device. The earliest Ogham inscriptions (4th–5th century CE) are purely phonetic — they record names and territories, with no evidence that the tree symbolism was attached at that early date. The elaborate tree meanings appear to develop in the manuscript tradition from around the 7th century onwards.

The Celtic Tree Calendar Controversy

In 1948, Robert Graves published The White Goddess, a book of poetic mythology that proposed a “Celtic Tree Calendar” based on the Ogham alphabet. In this theory, each letter corresponded to a month of the year, creating a sacred calendar of tree-months.

The problem: this calendar has no basis in the historical record. Medieval Irish manuscripts don’t describe a tree calendar. Modern Celtic scholars consider the Graves calendar a 20th-century invention — poetically compelling but historically unfounded.

This doesn’t make the tree associations meaningless. The genuine medieval tradition of tree-named letters is fascinating in its own right, without needing the embellishment of a fictional calendar.

Trees in Early Irish Culture

The association between trees and the sacred in Celtic culture is genuine and ancient. The word nemeton (a sacred grove or sanctuary) appears across the Celtic world from Galatia to Britain. Certain trees — the oak above all — were connected to ritual and ceremony. Druids, whose name may derive from a root meaning “oak knowledge,” are repeatedly associated with groves and tree-sacred practices.

In this context, an alphabet whose letters are named for trees is not surprising. It reflects a world in which trees were not background scenery but participants in the sacred landscape.

Explore each Ogham letter in detail on our Ogham alphabet page, or translate your name into Ogham.