Eustachys is a genus of tropical and subtropical grasses in the family Poaceae (order Poales), commonly known as fan grass or fingergrass. The genus comprises approximately 15 species distributed primarily across the warmer parts of the Americas, from the southeastern United States through Mexico, the West Indies, and Central and South America, with a smaller number of species native to Africa and Asia.
Members of Eustachys are perennial or annual grasses characterized by their digitate (finger-like) inflorescences — multiple spike-like racemes radiating from or near the apex of the stem, a morphology shared with the closely related genus Chloris. The genus was historically treated more broadly, and several species formerly placed in Eustachys have been reclassified into Chloris and, in the case of some bulbous species, into Ornithogalum (a different plant family entirely, reflecting past taxonomic confusion).
Notable species include Eustachys petraea, which has one of the widest ranges in the genus, extending from the eastern United States through the tropics to the Pacific Islands, and Eustachys paspaloides, which has a distinct distribution in the Arabian Peninsula and eastern and southern Africa. Several South American species — including Eustachys retusa, Eustachys distichophylla, and Eustachys calvescens — have naturalized in parts of the United States.
Distribution
Eustachys is native primarily to the warmer parts of the Americas, ranging from the southeastern United States south through Mexico, the West Indies, and Central and South America. A few species extend to Africa (eastern and southern Africa, Yemen, Oman) and southeastern Asia including New Guinea and southern China. Several South American species have naturalized in the United States.
Taxonomy Notes
Several species formerly placed in Eustachys have been reclassified: E. gayana, E. polystachya, and E. submutica are now treated under Chloris. Two species formerly included (E. latifolia, E. pyramidale) were moved to Ornithogalum — a genus in the family Asparagaceae — reflecting earlier broad and now-rejected circumscriptions of Eustachys.
