Crann Bethadh means tree of life in Old Irish. It’s an oak tree. The Celts used to plant them in the centers of their villages where they could be the axis mundi, the pillar holding everything up, the pivot around which it all turns. It’s a sacred world tree, and an older one than the one in the Old English Rune Poem, which stand right there next to it in order. In the Rune Poem, oak is the letter A, which comes right after D. In the Ogam alphabet written down in Old Irish, D is an oak. When they needed new runes for new sounds and invented the oak rune, they kept it close to its roots.
The Ogam alphabet uses bríatharogam to describe each letter name. These are two word descriptions that act as riddles or metaphors and work in a similar way to Old English kennings, which are either compound … More
Ogam, spelled Ogham in modern Irish, is an Old Irish alphabet, it was possibly a cryptographic alphabet like the runic ones, and it may have had its own sign language and musical notation. The Ogam letters have names like the letters in the Rune Poem, and the letters have meanings we can glean from three collections of 
