* USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network - (GRIN) [Data from 07-Oct-06]. 
Rigiopappus is a monotypic genus whose only species is Rigiopappus leptocladus. It is a flowering plant in the daisy family sometimes known as wireweed. It is an annual plant sending up slender stems terminating in small daisylike yellow flowers. It is native to the western United States. It is closely related to genus Pentachaeta.
Source: Wikipedia, Wikispecies: All text is available under the terms of the GNU Free Documentation License