RODENTS OF LIBYA 23 



and other sources of water. The genera most frequently found in 

 these mesic habitats are: Typha L., Potamogeton L., Phragrnites Trim, 

 and Cyperus L. 



Tripolitanian Gebel. The floral composition of the Tripolitanian 

 Gebel (Gebel Nefusa) differs markedly from that of the Cyrenaican 

 Plateau and has greater affinities with the flora of the Saharan steppe. 

 The vegetative cover of the Tripolitanian Gebel is sparser and con- 

 sists of a smaller assemblage of species. Grasses, chiefly Stipa L., 

 constitute the dominant element in the plant cover. Other plants 

 present on the Gebel, which are considered more typical of the 

 Saharan steppe, include Teucrium L., Lavandula L., and Rhamnus L. 

 Olive trees (Oka) occur in the less rugged areas of the Gebel, and date 

 palms (Phoenix dactylifera L.) are of localized occurrence on the 

 terraces of the coastal escarpment. 



Saharan steppe. The Saharan steppe, or transitional desert of Libya, 

 extends as a broad belt of scrub desert vegetation between the denser 

 plant cover of the coastal plain and the extremely sparse vegetative 

 cover of the Saharan interior. This semiarid region contains plant 

 species typical of both the Mediterranean and Saharo-Sindien Floral 

 Regions. In any given area of transitional desert, the vegetation tends 

 to be rather uniform and frequently large areas are dominated by 

 specific types. Several different types of steppes can thus be dis- 

 tinguished in Libya based upon the dominant plant occurring in each. 

 Chief among these types of steppe are the Asphodelus L. steppe, the 

 Artemisia L. steppe, and the Aristida-Stipa L. steppe. In the steppe 

 region south of the Cyrenaican Plateau and near the Gulf of Sirte, 

 the genera Asphodelus and Lygewm L. are common. The most widely 

 spread plant genus of the Libyan steppe is Aristida. The vegetative 

 cover of this semiarid region sometimes extends uninterruptedly for 

 200 kilometers or more but becomes more sporadic and localized near 

 the northern margins of the Sahara proper. In this steppe region, 

 acacia trees (usually Acacia radianna Savi) are not uncommon and 

 occur either singly or as small groups along the margins of the larger 

 wadis. 



Sand seas, hamadas, and serirs. In the sand seas the grass, Aristida 

 pungens Desf., is the dominant herbaceous plant. In areas where the 

 sand has become stabilized, plant cover is characterized by the follow- 

 ing arborescent genera: Ephedra, Retama Boiss., Genista DC, and 

 Cailigonum. Cyperus and Mottkia Lehm. are the most abundant 

 herbaceous plants. 



The sparse vegetative cover of the hamadas consists of several 

 characteristic genera which include Haloxylon deBunge, Fagonia, and 

 Fredolia Coss. and Dur. Following periods of rain, a variety of annual 



