A species with the habit of Aristida divaricata H. et B., but welldistinguished by the wanting column and the curious tuberculate lemmas. Closely allied to Aristida gentilis HENR., which differs however in the other position of the glumes and in the smooth lemma. The species resembles in some characters the Aristida Parishii HITCHC., the latter has however a totally different shape of the panicle and the lemma is not tuberculate-hispid, but scabrous only on the upper half. Among duplicates from the U. S. Nat. Herbarium, kindly received from Mrs. A. CHASE, I found a second plant belonging to the species, a plant also collected in Arizona, north slope of Santa Rita Mountains, leg. D. GRIFFITHS no. 7269.