View photos of the medicinal plant Gutierrezia sarothrae (Broom snakeweed), profiled in Medicinal Plants of the American Southwest.

A passage from Medicinal Plants of the American Southwest:

Snakeweed is mainly used externally to reduce joint soreness, particularly from rheumatoid arthritis. Being broadly antiinflammatory and especially sedative to muscular–skeletal pain, it will be found particularly helpful to sufferers of ‘fibromyalgia’.