A shrub or tree (genus Alnus) of the birch family that has special implications in Celtic tradition. The alder usually grows in wet ground, with small, pendulous catkins. Alders are especially associated with Bran; at Cad Goddeu, ‘The Battle of the Trees’, Gwydion guessed Bran's name from the alder twigs in his hand. The answer to an old Taliesin riddle ‘Why is the alder purple?’ is ‘Because Bran wore purple’. Bran's alder may be a symbol of resurrection. The name for the boy Gwern, son of Matholwch and Branwen, means ‘alder’. The place-name Fernmag (ang. Farney) means ‘plain of the alder’.
In Ireland the alder was regarded with awe apparently because when cut the wood turns from white to red. At one time the felling of an alder was punishable, and it is still avoided. The alder was thought to have power of divination, especially in the diagnosing of diseases. Alder or yew might be used in the fé, a rod for measuring corpses and graves in pre-Christian Ireland. The letter F, third consonant in the ogham alphabet, was named for the alder (OIr. fern). ModIr. fearnóg; ScG feàrna; Manx farney; W gwernen; Corn.gwernen; Bret. gwernenn. See also FAIRY TREE.