House Tyrell
"Growing strong": These are the words of House Tyrell. Tracing descent from Garth Greenhand, the first ruler of the Reach, who made the land bloom, like the other houses of the Reach. Once the stewards of the first ruling dynasty, House Gardener, following the purging of their king's line on the Field of Fire by dragonfire, they became the new rulers of their fertile realm by avoiding resistance to Aegon's conquest, becoming loyal subjects of the Targaryens. Now they follow the Baratheon dynasty loyally.
History
Kingdom of the Reach
Tracing descent via their women to Garth the Gardener, the founder of the Reach and it's first caretaker, the Tyrell bloodline emerged from an Andal knight, Alester Tyrell who was elevated by the Gardner dynasty. The Tyrells have since been faithful stewards to their kings, tending the fertile gardens of the Reach for their lords and ensuring they would always grow strong
Targaryen Rule
Their fortunes changed after their ruling House was purged along with their king at the Field of Fire at the hands of House Targaryen and their three dragons, after which Harlan Tyrell surrendered Highgarden to Aegon, who elevated them to Wardens of the South and Lord Paramount of the Reach. Due to Dorne resisting Aegon's conquest, their guardianship of the south led them into conflict against the Dornishmen.