A desert plant, Parthenium argentatum, of the composite family (Compositae), which produces rubber. It is a native perennial shrub growing in the Chihuahuan Desert of north-central Mexico and southwestern Texas. The plant is bushy with dense branches, thick clusters of silverlike leaves, a strong taproot, and a thick crown (see illus.). At maturity the plant varies in height from 30 to 40 in. (76 to 102 cm).