JOURNAL OF THEARNOLD ARBORETUMVOLUME 66 APRIL 1985 NUMBER 2 THE SUBFAMILIES AND TRIBES OF GRAMINEAE (POACEAE) IN THE SOUTHEASTERN UNITED STATES' CHRISTOPHER S. CAMPBELL THE FAMILY GRAMINEAE (POACEAE), the fourth largest family of floweringplants, is represented in the southeastern United States by about 575 species,130 genera, and 21 tribes assigned to five subfamilies. In number of genera itmatches the Compositae (Asteraceae) almost exactly and exceeds both theLeguminosae (Fabaceae) (ca. 72 genera) and the Orchidaceae (ca. 50 genera)in this area of some 444,000 square miles (1.15 million square kilometers).The present account contains a comprehensive family description; general 'Prepared for the Generic Flora of the Southeastern United States, a long-term project made possibleby grants from the National Science Foundation and at this writing supported by BSR-8111520(C. E. Wood, Jr., principal investigator), under which a part of this research was done, and BSR-8303100(N. G. Miller, principal investigator). This account, the 107th in the series, follows in general theformat established in the first paper (Jour. Arnold Arb. 39: 296-346. 1958) and continued to thepresent. It departs from this format in some respects, most notably in the APPENDIX (a data matrix)and in the single bibliography placed at the end of the paper, instead of a separate one under thefamily and each subfamily and tribe. Only references cited are included in the bibliography. In theinterest of readability, dates of papers referred to in the text usually are given, as in other papers ofthe series, only when needed to identify the reference. The area covered by the Generic Flora includesNorth and South Carolina, Georgia, Florida. Tennessee, Alabama, Mississippi. Arkansas, and Lou-isiana. The descriptions are based primarily on the plants of this area, with information aboutextraregional members of the family in brackets [ ]. I thank Carroll Wood for his support and guidance, his critical review of the manuscript, and hiswork on the nomenclature of the taxa in this paper. Mary E. Barkworth, David W. Hall, Walter S.Judd, Elizabeth A. Kellogg, John R. Reeder, Thomas R. Soderstrom, and John W. Thieret providedmany helpful comments. I am grateful to Elizabeth B. Schmidt and to Stephen A. Spongberg for theireditorial expertise. FIGURE 1 was drawn by Donna Marino, and FIGURE 2 is by Scott E. Bergquist. FIGURES 3-11 weredrawn by Karen Stoutsenberger in 1975, 1976. and 1977, largely under NSF Grant BMS-21469(C. E. Wood, Jr., principal investigator); Carroll Wood or Kenneth R. Robertson and the authorprepared the materials and supervised these illustrations. FIGURE 4 was based on living plants collectedby Norton Miller near Chapel Hill, North Carolina, and grown by Carroll Wood in Cambridge,Massachusetts.c President and Fellows of Harvard College, 1985.Journal of the Arnold Arboretum 66: 123-199. April, 1985.