From A Wiki of Ice and Fire
|Title||High Steward of Highgarden|
|Book||The World of Ice & Fire (mentioned)|
Gareth Tyrell was a head of House Tyrell and the first High Steward of Highgarden for House Gardener. He was the second son of Ser Alester Tyrell.
Unlike his elder brother, Gareth was of a more bookish bent and never achieved knighthood, choosing to serve as a royal steward instead.
Gareth and his son Leo performed their duties so well that the Gardeners made the office of High Steward hereditary.
- ↑ 1.0 1.1 1.2 The World of Ice & Fire, The Reach: House Tyrell.