Blossoming Fendlerbush...

(Fendlera rupicola) fills the air with a sickly sweet odor along the Colorado River that can't be exaggerated, and here's the culprit (click images to enlarge):

This yellow beauty is Fremont's mahonia  (Mahonia fremontii), but it's not nearly as pungent:

The Colorado Plateau is just beginning to show its colors this spring as the parade of flowering plants commences.