East end of a cross levee on Robert's Island. Clay soil.
Tall grasses, growing along a fence line on MetroLink rail right of way, San Dimas Canyon Road, just S of Arrow Highway. Inflorescences distinctly red. Coin used for scale is a US quarter dollar (¢25 piece), 24.26 mm, 0.955 inch in diameter. Last photo taken some steps away from point of collection, so ignore the different looking soil in the background.
On the shore of Little Chippewa Lake
Sorghum bicolor
http://biology.burke.washington.edu/herbarium/imagecollection.php?Genus=Sorghum&Species=bicolor
If this is wrong, thenI am stumped as to what it might be.