Root (143no) remained the cornerstone as the hosts moved from 219 for two to 315 for four, in reply to 285 all out, in a session interrupted by one mid-morning shower and restricted to 22 overs.
Nightwatchman Chris Wright lasted four of those, edging Trent Boult to slip when the left-armer found just enough movement slanted across him.
Then James Taylor, as expected left out of the England reckoning when a 12-man squad for next week's first Test was announced, could find no consolation out in the middle.
He mustered two runs before falling to a shot he would doubtless prefer to forget quickly, sparring on the back foot and edging behind.
Root was still making no such mistakes as he and his Yorkshire and England team-mate Jonny Bairstow (45no) pressed on past 300 in an unbroken stand of 81.
- Sports & Recreation