Medicinal plants, eh? The kind that look like little buttons, and alter one’s perception? Just kidding. I should learn more about the plant life around here.
I’ve not personally experienced that bumping-into thing, and wouldn’t rely on it. I just watch and listen, and if I become aware of many bees, I retreat. Fortunately, the weather is cooler during deer and quail seasons, so bees are somewhat less active then. Still see them on warmer days, though.
If you're interested in medicinal plants in AZ this is the book you should take a look at.
Medicinal Plants of the Desert and Canyon West - Michael Moore
I went to his school in '94 when it was in Albuquerque. His other books about western medicinal plants are the best there are. He was one of the best American herbalists there was.