Shrubby Mayweed

I think I've found out what this is: Oncosiphon suffruticosum. The photo at this website has the best likeness to what I saw along the Gila River. Ironically enough this website appears to be from South Africa: http://www.plantzafrica.com/plantnop/oncosiphsuff.htm

I looked at the Wikipedia reference for Matricaria sp. and found one that looks close - Matricaria discoidea. According to Wikipedia it is found in Arizona. Wikipedia states that it is also found in disturbed areas. The spot where I found it was along a rocky shoreline of the Gila River where the water level changes. There is also some stream restoration going on nearby. The only difference is that the yellow flower on top on the one I saw doesn't have the wide fleshy stem underneath. Using Plants of Arizona, which I've found to be reasonably reliable, I couldn't find any listings in the index for Chamomile, Matricaria, or Lamiaceae.

Thanks very much, Bernadette. I looked in Plants of Arizona by Anne Orple Epple and it lists two species of Artemesia in Arizona: filifolia (Sand Sagebrush) and franseroides (Ragweed Sagebrush). From the color pictures the shape and the size don't quite match what I saw. The plants I saw were about 2.5 - 3.0 feet in diameter and at the most 2.5 feet tall. It might be a similar genus or something a exotic not listed in the Plants of Arizona. When you touch the plants you get a strong scent on your hands. It was something like what you'd get from a Sage but seemed more powerful and almost like licorice.