Ogham (᚛ᚑᚌᚐᚋ᚜) is an alphabet that appears on monumental inscriptions dating from the 4th to the 6th century AD, and in manuscripts dating from the 6th to the 9th century. It was used mainly to write Primitive and Old Irish, and also to write Old Welsh, Pictish and Latin. It was inscribed on stone monuments throughout Ireland, particuarly Kerry, Cork and Waterford, and in England, Scotland, the Isle of Man and Wales, particularly in Pembrokeshire in south Wales. (...)
The Ogham. ( pronounced OH-am or OH-yam ) , is also know as the Druid's Alphabet. The letters correspond to their 20 sacred trees. The 25-letter alphabet was supposedly inspired by Ogma, god of eloquence. The letters are strung together along a central line, either vertically or horizontally, in which case the letters are rotated.
The Celtic Tree Calendar is based on the Ogham alphabet and its association with trees. It consists of 13 months, each 28 days long, following the lunar cycle, as Roman accounts have suggested the Druids did, with one extra day representing the 23rd December, the ‘Day of Creation’. Each of the 13 months is represented by a tree together with its Ogham letter.