A genus of 6 species, annual herbs, of North America south into Mexico and disjunct in South America. This genus has been segregated from Draba on molecular and morphological grounds (Jordon-Thaden et al. 2010; Al-Shehbaz 2012).
Ref: Al-Shehbaz (1987); Al-Shehbaz (2012a); Al-Shehbaz, Windham, & Elven (2010) In Flora of North America Editorial Committee (2010); Jordon-Thaden et al. (2010); Koch & Al-Shehbaz (2002); Rollins (1993). Show full citations.