IRAN 43 



by the great barrier of Zagros, rising precipitously from 

 the narrow coastal shelf of the Persian Gulf. 



Its central situation in the midst of arid lands, and 

 its girdle of lofty mountains mark it, from the first, as 

 a very dry territory, whilst its elevation, which, in the 

 south-west, is considerable, and its extra-tropical position, 

 make it a land of extremes of heat and cold. Except in 

 the north-west, the yearly rainfall remains under ten 

 inches and is very unreliable. The worst feature is 

 the icy northern blast which sweeps unchecked across the 

 eastern plains. Here again, therefore, the life of the 

 country depends largely on the snows of the marginal 

 mountains, and of the two chains which cross the plateau. 

 These feed meagre streams, which dry up and lose them- 

 selves at no great distance from the foot-hills. 



Under such circumstances, forest-growth is out of 

 question ; even large tracts of continuous grassland are 

 scarce. Loose colonies of plants form the essential feature, 

 and these are necessarily confined to isolated localities 

 of limited extent, conditioned solely by the nature of 

 the relief and the soil. The dry winds keep the vegeta- 

 tion low : trees require the shelter of the mountains, 

 but low shrubs, scattered and deciduous, able to tap 

 the deep-seated ground-water, are best adapted to these 

 conditions, and with them an ephemeral flora, which 

 bursts forth with the occasional showery spells and then 

 dies. Perhaps the chief characteristic of the Persian 

 vegetation is the extraordinary wealth of thorns and 

 prickles : about five hundred thorny plants have been 

 counted here, including small trees, shrubs, under-shrubs, 

 and perennials. 



An important distinction must be drawn between the 

 broad valley of Shiraz-Isfahan, which rises like a vast 

 hummock between the southern chain of Iran and the 



