House Oakheart of Old Oak is one of the oldest of the Reach houses sworn to Highgarden, descended in song and lineage from Garth Greenhand by way of his son Beldan the Brave. Their seat, Old Oak, is built around an ancient weirwood-sized oak tree the smallfolk swear was already old when the First Men first came south.
Lord Arwyn Oakheart holds Old Oak; her son Ser Arys serves in the Kingsguard of King Robert Baratheon, white cloak about his shoulders and three oak leaves on his shield.