BRIZICKY, GENERA OF RHAMNACEAE THE GENERA OF RHAMNACEAE IN THE SOUTHEASTERN UNITED STATES 1 GEORGE K. BRIZICKY RHAMNACEAE A. L. de Jussieu, Gen. P1. 376. 1789, "Rhamni," nom. cons. (BUCKTHORN FAMILY.) Deciduous or evergreen trees, shrubs, or woody vines [exceptionally herbs], unarmed or armed with thorns or stipular spines. Leaves simple, alternate, subopposite, or opposite, petiolate; stipules mostly free, more rarely connate across the axil, usually minute and caducous, sometimes modified to spines Irarely absent). Inflorescences axillary few-flowered umbel-or corymb-like cymes (sometimes reduced to a solitary flower), or axillary and/or terminal raceme-or spikelike thyrses. Flowers small or minute, regular, perigynous to epigynous, with a distinct floral tube, bi-and/or unisexual by abortion, pediceled or sessile. Floral tube ("hypan-thium") patelliform to hemispherical or campanulate [or urceolate to cylindrical], persistent in fruit at least in part; calyx lobes usually 4 or 5. valvate in aestivation, usually deciduous either separately or with the sometimes circumscissile upper part of the floral tube, rarely persistent. Petals 4 or 5, alternate with the calyx lobes, � concave or hooded or flat, often clawed, enfolding the stamens in aestivation, or wanting. Stamens 4 or 5. opposite the petals, adnate to them at the base and inserted at or below the margin of the disc, smaller and sterile in 9 flowers; filaments usually subulate, longer or sometimes slightly shorter than the anthers; anthers dorsifixed, usually nonversatile, 2-locular at anthesis, longitudinally dehiscent; pollen usually 3-colporate, suboblate to subprolate, small to medium sized, often � triangular in polar view. � smooth to reticulate. Nectariferous disc intrastaminal, hypogynous to epigynous [rarely want-ing]. Gynoecium 2-or 314]-carpellate, syncarpous, rudimentary in d SPrepared for a generic flora of the southeastern United States, a joint project ofthe Gray Herbarium and the Arnold Arboretum 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 40-45 (1959-1964). The areacovered is bounded by and includes North Carolina, Tennessee, Arkansas, andLouisiana. 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 J. Rzedowski, Escuela Nacional de Ciencias Biol6gicas, Mexico, D. F., for supplyingreferences to the distribution of Berchemia scandens in Mexico; and to Mrs. GordonW. Dillon for her help in the preparation of the typescript.1964]
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