424 TRAVELLING BUSHES BLOWN BY THE WIND. 



growth are consequently very short, and this in a 

 measure doubtless accounts for their closely cropped 

 appearance ; the necessity for mutual protection against 

 the violence of the sudden storms to which the desert 

 is so liable will also account for their gregarious habit 

 of growth in clumps or thickets. When they grow 

 singly, or on the outskirts of copses and in positions 

 where they are apt to be blown down by storms, 

 another curious feature about these trees is that when 

 uprooted they travel about the desert in an extraordinary 

 manner ; being driven about by the force of the wind 

 from one place to another, much as an open umbrella 

 would be, and yet Solymos tells us that under these 

 circumstances they still continue to live on "appar- 

 ently for years, " * thus showing how little these curious 

 trees, when once fully developed, are dependent on the 

 soil for their vitality. When circumstances admit of 

 it, it is more than probable that many of them in the 

 end become embedded in the sands, and taking root 

 again form the nucleus of new plantations at other points. 



The rest of the vegetation may be said to consist 

 mainly of herbs, bulbous plants, and grasses ; even in 

 the most barren situations, many bulbs full of sap will 

 be found by those who know how and where to seek for 

 them, and occasional tufts of some kind of herbage 

 are rarely entirely absent. Some of these grasses are 

 of an exceedingly valuable character. 



The now well-known " Esparto grass " (Stipa Tena- 

 cissimd) of North Africa, known as " Haifa " by the 

 Arabs, which has lately been so largely exported 



* Desert Life, by B. Solymos, 1880, p. 64. (N.B. The great 

 probabilities are that though these little trees are much dwarfed, still 

 their age, measured in years, is considerable.) 



