Sudanian Elements in the Flora of Israel

Abstract

In the Dead Sea Rift Valley of Israel, a northern tongue of penetration of Sudanian elements exists that has traditionally been regarded as composed of Miocene relicts. We postulate that most of these elements have penetrated the area since the end of the Pleistocene. The principal habitats harboring Sudanian elements in Israel are described, including the pseudo-savanna in wadi beds, cliffs and rock formation, oases and in the Dead Sea Rift as well as a variety of secondary habitats outside the Rift. In addition, a statistical analysis of the 116 species in the flora of Israel considered to be Sudanian elements is presented, covering growth form, phytogeographic distribution, dispersal mechanisms, and degree of endemism. Special attention is given to the arboreal elements, including 49 species of trees, shrubs, and perennial vines. A comparison is made between the habitats of these species in East Africa and in Israel: significant habitat shifts were found in some cases. Although paleo-macrofossils are almost non-existent in the area, other evidence, such as low degree of endemism, disjunctiveness, and adaptations to aridity and long-distance dispersal indicate that the great majority of the Sudanian elements in the Dead Sea Rift are of recent origin. The relationships between the typical evergreen Mediterranean elements with paleotropical origins and the extant Sudanian elements in Israel are discussed. Within the portion of the Syrian-African Rift lying between the Red Sea to the south and the watershed of the Jordan River in the Golan Heights, a large number of Sudanian elements, plants as well as animals, are found considerably farther north than anywhere else in their distribution range and in many cases growing under ecological conditions quite different from their norm. In addition, a handful of Sudanian species also occur in the low-lying coastal plain of Israel, almost entirely cut off from the Dead Sea Rift Valley and the bulk of the Sudanian region proper (Fig. 1). Climatic and geological conditions in the Dead Sea Rift Valley explain in part the presI A. Shmida wishes to express his considerable debt of gratitude to the late Prof. M. Zohary who introduced him (and dozens of other students) to the intricacies and unique attributes of the Israeli flora. We thank G. E. Wickens who reviewed the manuscript with meticulous care, helped gather information for some of the distribution maps, and made valuable suggestions for improvement of the text. J. B. Gillett and P. Quezel also kindly reviewed the manuscript and provided stimulating comments and suggestions. Our thanks also go to Sandy Greenberg, Seemah Shemesh, and Marion Milner who provided computer and typing assistance, to Nancy R. Morin and Dr. Marjorie Tiefert for patient and professional editorial guidance, and to Miri Shmida who drew the figures. The assistance of J. Dransfield in preparing Figure 5 is gratefully acknowledged. Any errors or inaccuracies therein are entirely the responsibility of the authors. Finally we thank the numerous guides of the Israeli Society for the Protection of Nature who helped us locate some of the rare and little-known populations of Sudanian plants in Israel. We gratefully acknowledge financial assistance received during the course of this research from the Bath-sheva de Rothschild Fund to A. Shmida and the Clifford M. Hardin Fund of the Fund for Higher Education to J. A. Aronson. 2 Department of Botany, The Hebrew University of Jerusalem, Jerusalem, Israel. 3Rudolf and Rhoda Boyko Institute for Agriculture and Applied Biology, Institutes for Applied Research, Ben-Gurion University of the Negev, P.O. Box 1025, Beer-Sheva 84110, Israel. ANN. MissouRi BOT. GARD. 73: 1-28. 1986. This content downloaded from 157.55.39.253 on Sat, 11 Jun 2016 07:14:14 UTC All use subject to http://about.jstor.org/terms 2 ANNALS OF THE MISSOURI BOTANICAL GARDEN [VOL. 73