Oreochrysum Rydb. includes one herbaceous perennial species O. parryi (synonyms: Haplopappus parryi, Solidago parryi) native to western North America. It is related to Solidago, Tonestus, Petradoria and Hesperadoria and the aster genus Sericocarpus. Semple et al. (1999) included it as a subgenus within Solidago based on the results of Zhang's (1996) cpDNA RFLP study. Subsequently, studies suggested Oreochrysum falls outside Solidago (Beck et al. 2004) and it is treated as a separate genus here and by Nesom (2006, Flora North America).