Dropping Sulu meant pretty much dropping him into a set of gnashing teeth trying to eat phaser fire (failing, but still trying), but Sulu was resourceful enough to keep hold of the flailing root, swinging off of it onto the ground some (relatively) safe distance away, now that the thing was distracted.

What with it being distracted, it didn't notice him with his sword, ducking right back in to hack at the roots advancing on McCoy. "Thank you, Captain," he shouted - just to be a smartass.