Ambrosia trifida L.

A common species in the eastern United States, uncommon and limited to low-elevation cienegas, riparian habitats, &c. in the southwestern U.S.

Inflorescences at Wagon Mound Cienega, Mora County, New Mexico, 7 Aug 2011.

A middle cauline leaf at Wagon Mound Cienega, 7 Aug 2011.

Staminate pseudanthia at Wagon Mound Cienega, 7 Aug 2011.