Pterogonum atrorubens (Engelmann) H. Gross

Varieties 5 (1 in the flora): w North America, including n Mexico.

All five varieties occur in northern Mexico (Chihuahua, Coahuila, Durango, Nuevo León, Sonora, and Zacatecas) in oak and conifer woodlands, commonly above 2200 m elevation. In addition to var. atrorubens (including var. psuedociliatum Reveal), they are var. auritulum W. J. Hess & Reveal, var. intonsum Reveal, var. nemorosum W. J. Hess & Reveal, and var. rupestre (S. Stokes) W. J. Hess & Reveal.