A taxonomic revision of Psathyrostachys (Poaceae)

The genus Psathyrostachys is revised. A total of 23 taxa had previously been described, now the following taxa are recognized: P. fragilis ssp. fragilis (2n = 14), P. fragilis ssp. secaliformis, P. fragilis ssp. villosus ssp. nov., P. caduca, P. huashanica (2n = 14), P. rupestris ssp. rupestris, P. rupestris ssp. daghestanica, P. lanuginosa (2n = 14 and 28), P. kronenburgii, P. juncea (2n = 14), and P. stoloniformis (2n = 14). A previous infrageneric division into sections cannot be recognized. A key, descriptions, nomenclature, illustrations, distribution maps, and cytogenetic data are presented.