Mystery Plant + three clues

Clue #1, the site:

Clue #2, habitat:

Mystery plants in foreground, coyote willows behind.

The Mystery Plant:

Several mystery plants; note red stems.

Buds, flowers and fruit.

Flowers turn pink with age.

Recognize this plant?  Or the genus or family?  It's a rare species but the genus and family are common on the Great Plains (North America).  You can offer your opinion as a Comment below.  The answer and more will follow in about a week.  Update:  Answer is HERE.

Clue #3, where on Google Earth (click on image for a closer view):