Nabalus asper (formerly Prenanthes aspera), commonly called the rough rattlesnakeroot or rough white lettuce, is a species of plant in the family Asteraceae occurring in the eastern United States from South Dakota and Pennsylvania south to Oklahoma, Louisiana, and Alabama. This perennial plant blooms in late summer and autumn. In 2010, it was reclassified from the genus Prenanthes to Nabalus.

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