The 17th letter of the
Ogham tree alphabet, representing the letter O and meaning "furze."
Furze, or gorse, is loved by bees and symbolizes the collecting of valuable knowledge, In many ways gorse symbolizes testing and purification. Ohn indicates that you should make use of the knowledge you already have, or acquire the necessary knowledge, to achieve wisdom and mastery.
SOURCE: Omens, Oghams & Oracles, Richard Webster