A Revision of the Mexican Endemic Asta (Brassicaceae)
The monospecific, Mexican endemic Asta Klotzsch & O. E. Schulz is divided into three subpecies. The new combinations A. schaffneri (S. Watson) O. E. Schulz subsp. pringlei (O. E. Schulz) Al-Shehbaz and A. schaffneri subsp. stricta (Rollins) Al-Shehbaz are proposed. Asta schaffneri subsp. pringlei is widespread in east-central Mexico, A. schaffneri subsp. schaffneri is endemic to San Luis Potosí, and A. schaffneri subsp. stricta is restricted to Hidalgo and Queretaro States. A key to the three subspecies is presented, and a neotype for A. pringlei O. E. Schulz is designated.