Turtle Mountain Provincial Park, Manitoba
When applied to the stamens, upper and lower refer to the point of attachment on the corolla tube. Lower means closer to the base of the corolla tube and upper means farther away from the base.
Flora of the Great Plains states that the upper pair of stamens is exserted between the lower pair. This is true; the upper stamens cross the lower ones in the portion of the corolla tube obscured by the lower lip in this picture.
Agastache: Answers to key questions in Budd's Flora and Flora of Alberta leading to this genus.
Labiatae: Answers to key questions in Budd's Flora leading to this family.