JOURNAL OF THE ARNOLD ARBORETUMIVOL. XLV THE GENERA OF CELASTRALES IN THE SOUTHEASTERN UNITED STATES I GEORGE K. BRIZICKY THE ORDER CELASTRALES, as delimited here, includes the familiesCelastraceae, Hippocrateaceae, and Aquifoliaceae, as well as several otherallied families (e.g., Siphonodontaceae, Stackhousiaceae) not representedin the southeastern United States. The Staphyleaceae, usually regarded asmembers of either Celastrales or Sapindales, are excluded from both theseorders, and will be treated within Cunoniales (or Saxifragales sensu lato),where they seem to belong (cf. C. G. G. J. van Steenis, Fl. Males. I. 6:49. 1960).CELASTRACEAE R. Brown in Flinders. Voy. Terra Austr. 2: 554. 1814, "Celastrinae," nom. cons. (STAFF-TREE FAMILY) Usually glabrous trees or shrubs, rarely woody vines, sometimes gutta-percha for rubber] bearing; nodes unilacunar. Leaves simple, mem-branaceous to coriaceous, opposite or alternate I rarely minute or rudi-mentary], petiolate, deciduous or persistent; stipules minute, usuallycaducous. Inflorescences axillary and/or terminal, cymose (usually dicho-tomously branched) or racemose, or the flowers solitary and/or fascicledin the leaf axils. Flowers small, regular, hypogynous, perigynous, or semi-epigynous, bisexual or unisexual by abortion (the plants then monoeciousor dioecious), pediceled (except Gyminda). Sepals 4 or 5, small, connateabout half of their length or more, or nearly distinct, usually imbricate. SPrepared for a generic flora of the southeastern United States, a joint project ofthe Arnold Arboretum and the Gray Herbarium of Harvard University made possiblethrough the support of George R. Cooley and the National Science Foundation andunder the direction of Carroll E. Wood, Jr., and Reed C. Rollins. This treatmentfollows the pattern established in the first paper in the series (Jour. Arnold Arb. 39:296-346. 1958) and continued through those in volumes 40 44 (1959-1963). The areacovered is bounded by and includes North Carolina, Tennessee, Arkansas, and Ioui-siana. The descriptions are based primarily on the plants of this area, with anysupplementary material in brackets. References which the author has not seen aremarked by an asterisk. The author is indebted to Carroll E. Wood, Jr., for his many valuable suggestions;to Harry Ahles, George R. Cooley, Wilbur H. Duncan, and James W. Hardin, forchecking herbarium records on the distribution of some genera of Celastraceae,especially Paxistima, in the southeastern United States; and to Mrs. Gordon W.Dillon, for her help in preparation of the manuscript. The illustration of Euonymuswas drawn by Dorothy H. Marsh, in part from fresh fruiting material sent by R. B.Channell.