Piptochaetium virescens var. arsenii (Hack.) Beetle Piptochaetium virescens var. arsenii (Hack.) Beetle in Phytologia 54(1): 4. 1983 sec. Dávila & al. 2018≡Stipa arsenii Hack. in Repert. Spec. Nov. Regni Veg. 8: 515. 1910 syn. sec. Dávila & al. 2006