From the CA Extension offices:
Sweet resinbush (Euryops subcarnosus) is an exotic species from South Africa that was introduced in Arizona during the 1930’s. It was brought here in hopes that it would provide forage for livestock and aid in slowing soil erosion. Potted plants were sent to Civilian Conservation Corps camps in 1935 where they were planted in study plots. Records show that the planting trials did not show promise and after several years of observations, the plantings were forgotten. During the 1970’s, some people noticed sweet resinbush starting to increase in certain parts of the state. By the 1990’s, it became evident that there was a need to be concerned about this plant. Sweet resinbush is a medium size shrub that usually grows less than 3 feet tall. The small leaves are divided and are often described as looking like turkey tracks. The plants bloom in response to winter moisture, usually in late winter and early spring. The name sweet resinbush comes from the sweet, but unpleasant smelling blooms and the drops of resin on the stems. Belonging to the sunflower family, sweet resinbush has many small, daisy-like flowers that produce many seeds.
The seeds are hairy and when wet, secrete a gelatin-like substance that sticks to anything that brushes by it. This being the case, it can spread to new locations by attaching to clothing, shoes and socks, vehicles, and the fur of wild and domestic animals. It can also be moved to new locations via water movement.
Why the concern over this shrub? Contrary to the intended goals of increasing forage for livestock and reducing erosion, sweet resinbush does just the opposite. The plant encroaches into healthy grasslands, choking out native vegetation. It then forms a monoculture of resinbush with large amounts of bare soil, leading to increased soil erosion. The original 12 potted plants on Frye Mesa (near Thatcher) have grown to an infestation covering approximately 3,000 acres. Not all of the area is heavily infested, but the threat of an ever increasing infestation is real. Other smaller infestations are located near Safford, Tucson, Globe, Miami, Punkin Center, and Cottonwood.