Scottish Gaelic orthography has evolved over many centuries and is heavily etymologizing in its modern form.
[5] The early Medieval treatise Auraicept na n-Éces ('The Scholars' Primer') describes the origin of alphabets from the Tower of Babel.
It assigns plant names and meanings to the Ogham alphabet, to a lesser extent to Norse Younger Futhark runes, and by extension to Latin letters when used to write Gaelic.
Robert Graves' book The White Goddess has been a major influence on assigning divinatory meanings to the tree symbolism.
In unstressed syllables, the range of vowels is highly restricted, mainly /ə, ɪ, a/ appearing and on occasion /ɔ/.
Only certain vowel graphs appear in unstressed syllables: ⟨a, ai, e, ea, ei, i⟩ and very infrequently ⟨o, oi, u, ui⟩.