It's the signature tree of the mountain West. President Obama and his family surely saw plenty of Ponderosas during Sunday's visit to the Grand Canyon ... And they begin to smell a bit strange ...

Visitors to the Grand ... the canyon is desert (Lower Sonoran). It also includes the river, which is surrounded by riparian vegetation and animals, such as willows, arrow weed, canyon tree frogs ...

Here's what each scent smells like, along with where you can get them: Desert Citrus: Grand Canyon National ... imagine the fresh smell of a Christmas tree). It's not unpleasant, but a scent ...