When Seph is trying to get into Trinity for the first time, he ends up waiting around near a farmhouse with wild roses:
They'd chosen a spot where the barrier cut across a field. A battered farmhouse crouched next to the road, its paint gone gray with weather. The foundation of the house was overgrown with wild roses, sprays of red and white flowers with yellow centers. In the pasture, cattle wandered back and forth through the barrier, oblivious to it. The late day sun slanted across the barnyard.
The Wizard Heir, Chapter 10: "The Weirweb"
I might have dismissed this as simple scene-setting if only the type of flower was noted, but the mentioned of colors perked my interest. The Red and White Roses are the dueling wizard houses, the main centers of power in this setting, and were the main antagonist factions in the previous book. (They're still around in The Wizard Heir, but less so than The Warrior Heir, due to the introduction of new antagonists.) Therefore, I assume that specifically having red and white roses appear holds some significance. What would that be?