PREFACE. ^ XV 



of Huleh, though long since extinct in Egypt, and not now known in 

 Africa further north than on the White Nile, lat. 7° N. Calotropis 

 procera and Salvadora persica are never found except close to the Dead 

 Sea, at Engedi, Safieh, and Seisaban, and are separated by many 

 degrees of longitude and latitude from their other known habitats. It is 

 also interesting to observe that of the 135 African species in Wady 

 Zuweirah, 23 extend as far west as the Canaries, and 17 are decidedly 

 Arabian, being included in the Flora of Aden. None of these African 

 forms occur in other parts of Palestine. 



While it is not probable that many other European plants have 

 escaped observation on the shore of the Dead Sea, as they would 

 naturally be early flowerers, many other decidedly tropical plants not 

 included in those gathered in Wady Zuweirah in February have been 

 noted in hasty visits to the district later in the year. Such are Abutilon 

 inutic2ivi ?vcidi A. fruticosiuii, Zygophylliim coccinetiin, Indigofera argcntea., 

 Boerhavia plwnbaginea, Conyza dioscoridis, etc. 



There are other very remarkable contrasts in the affinities of the 

 Flora. Thus among the Legiiminoscs, there are no less than 50 species 

 of Trifolmm, and 74 species of Astragabis in our list. Of the former 

 only one, T. sienophyihini, is found in the south, and not one in the 

 Jordan valley; and all of them are either European, or have European 

 affinities. There is no indication of any species connected with the 

 Himalayas or Central Asia. Of the 74 Astragali, on the contrary, only 

 3 have any Palaearctic affinities ; all the others are either Indian, or 

 belong exclusively to the Oriental or Ethiopian regions. Yet the 

 Astragali are by no means confined to the Jordan valley. No less than 

 35 species are strictly limited to the mountain and alpine regions of 

 Lebanon and Anti- Lebanon. The bulk of the remainder belong to the 

 Jordan valley and Southern Desert, and if found elsewhere are either in 

 Scinde or Africa. 



The Flora of the Dead Sea area is remarkable for a small average 

 number of species distributed through a large number of orders. In 250 

 species collected on the east side of the Dead Sea in February, 58 orders 

 were represented, an average of 4^ species to each order. We may infer 

 that in this borderland of Europe, Asia, and Africa, the more hardy and 

 accommodating plants of each area hold their own, while those more 

 readily affected by variation of soil or climate disappear. 



