The Tyrells rose to power as stewards to the Kings of the Reach, whose domain included the fertile plains of the southwest from the Dornish marches and Blackwater Rush to the shores of the Sunset Sea. Through the female line, they claim descent from Garth Greenhand, gardener king of the First Men, who wore a crown of vines and flowers and made the land bloom. When Mern IX, last king of House Gardener, was slain on the Field of Fire, his steward Harlen Tyrell surrendered Highgarden to Aegon the Conqueror. Aegon granted him the castle and dominion over the Reach. The Tyrell sigil is a golden rose on a grass-green field. Their words are Growing Strong.