Zuloaga, Fernando O., and Thomas R. Soderstrom. Classification of the Outlying Species of New World Panicum (Poaceae: Paniceae). Smithsonian Contributions to Botany, number 59, 63 pages, 25 figures, 2 tables, 1985.—In the present study a number of species originally assigned to Panicum but not fitting well within its boundaries have been examined. Some of the characters that have been used in the past to distinguish genera in the tribe have been re-examined, including type of hilum, spikelet compression, relative length of the glumes, consistency of the upper anthecium and whether crested or not, and carriage of the spikelet relative to the axis. Further characters of taxonomic importance have been revealed by studies made with the scanning electron microscope (SEM) at higher magnifications than previously possible. The results of these studies indicate that several species should be removed from Panicum and transferred to other genera. Accordingly the following changes have been made: P. megastachyum Nees ex Trinius and P. albicomum Swallen & García Barriga have been transferred to Brachiaria, P. glutinosum Swartz and P. villaricense Mez to Homolepis, P. grandifolium Doell to Ichnanthus, P. killipii Hitchcock to Paspalum, and P. macranthum Trinius to Streptostachys. Panicum arnacites Trinius forms the basis of a new genus, Tatianyx. With these changes in content the descriptions of Homolepis and Streptostachys are emended, two new species-Brachiaria tatianae and Streptostachys ramosa-are described, and the unusual species P. aristellum Doell is characterized and a possible relationship discussed. A chart is presented that compares the characters of the genera covered in the present investigation, P. aristellum and the two new species are illustrated, and SEM photomicrographs of all taxa are included.