JOURNAL OF THEARNOLD ARBORETUMVOL. 46 APRIL 1965 NUMBER 2 THE GENERA OF POLYGONACEAE IN THE SOUTHEASTERN UNITED STATES1 SHIRLEY A. GRAHAM AND C. E. WOOD, JR. POLYGONACEAE A. L. de Jussieu, Gen. P1. 82. 1789, "Polygoneae." nom. cons. (BUCKWHEAT FAMILY) Annual or perennial herbs, shrubs, trees, or vines, often with conspicu-ously swollen nodes, the nodes completely or partly surrounded by a mem-branaceous or scarious sheath, the ocrea, or this reduced to a row of hairsor completely wanting in a few genera. Leaves entire [rarely pinnatifid orpalmately cleft], alternate or whorled [or opposite], petiolate to sessile.membranaceous to fleshy or leathery, occasionally articulated at the basewith the stem. Inflorescences diverse, the flowers seldom solitary, mostlyclustered into few-flowered fascicles, each fascicle subtended by a bractand each flower by a persistent sheath (ocreola) and occasionally also by2 scarious bractlets; rarely fascicles subtended by and partly included inan involucre, the flowers subtended at the base only by numerous bractlets.Flowers regular, with a variable number of parts, mostly 3-or 5-merous.bisexual or unisexual, the base (receptacle?) narrowed into a short orlong stipe which articulates with the pedicel. Tepals (2-) 5 or 6. in 2 SPrepared for a generic flora of the southeastern United States, a joint project ofthe Gray Herbarium and the Arnold Arboretum made possible through the supportof George R. Cooley and the National Science Foundation and under the direction ofReed C. Rollins and Carroll E. Wood, Jr. The scheme follows that outlined at thebeginning of the series (Jour. Arnold Arb. 39: 296-346. 1958). The area covered inthis, as in former treatments, is bounded by and includes North Carolina, Tennessee,Arkansas, and Louisiana. Material included in the descriptions in brackets applies tospecies outside this area, and references marked by an asterisk have not been seen bythe authors. Drs. Richard A. Howard and Ben W. Smith have reviewed the treatments ofCoccoloba and of Rumex subg. Acetosa, respectively; their suggestions and correctionsare gratefully acknowledged. Dr. Howard has generously allowed us to report twochromosome counts made by him; and Dr. R. B. Channell collected excellent floweringand fruiting material which has been indispensable in the study of Brunnichia. Theillustrations were prepared by Arnold D. Clapman.