Apart from the Atlantic and Gulf coastal plain, this zone includes a large part of the eastern United States. In the north it extends into southern Canada to include southeastern Ontario and southern Quebec while in the south it extends to central Georgia, central Alabama, parts of eastern Texas and includes much of Arkansas. Its western boundary extends to Minnesota, eastern Iowa, the Ozark Plateau and the Quachita Mountains.
Endemic and near endemic vascular plants so far recorded for this zone include 200 species in 150 genera and 63 families but there are no endemic genera or families. However, the Hamamelidaceae use to be much more widely distributed in the Northern Hemisphere during the Upper Cretaceous and early Tertiary. Many species became extinct during the Ice Age but a number survived in tropical and subtropical mountains and in the Caucasus region.
Estill, J. C. & Cruzan, M. B. 2001. Phytogeography of rare plant species endemic to the southeastern United States. Castanea, 66: 3-23.
Keener, C. S. 1983. Distribution and biohistory of the endemic flora of the Mid-Appalachian Shale Barrens. The Botanical Review, 49: 65-115.
Pittillo, J. D. & Smathers, G. A. 1979. Phytogeography of the Balsam Mountains and Pisgah Ridge, Southern Appalachian Mountains. In: Contributions to the knowledge of flora and vegetation in the Carolinas. Eds. H. Leith and E. Landolt. VGI Zurich.
Qian, H. 1999. Floristic analysis of vascular plant genera of North America north of Mexico: characterization and phytogeography. Journal of Biogeography, 26: 1307-1321.
Zhi-yun, Z. & An-ming, L. 1995. Hamamelidaceae: Geographic distribution, fossil history and origin. Acta Phytotaxonomica Sinica, 33: 313–339.