TORREYA 



Vol. II 



April, igii 



No. 4 



SOME FLORAL FEATURES OF MEXICO* 



By H. H. Rusby 



At a rough estimate, two thirds of Mexican territory is arid, 

 and nearly half of this can be considered a desert, in that it 

 cannot naturally support grazing animals. 



The fertile region includes (i) the lowland of the south, with a 

 tropical climate, and amidst which there are numerous mountains 

 possessing a subtropical, or some of them even a temperate 

 climate, and which gradually changes into an arid region as it 

 rises into the central table-land; (2) an eastern or Gulf Coast 

 strip which, gradually narrowing, extends from the southern 

 tropics clear up into Texas; (3) a Pacific Coast strip which, 

 narrow at all points, gives way northward to the desert region 

 of and adjacent to the Peninsula of California. 



Within these boundaries, and stretching to the Rio Grande, 

 is the arid region, of which more than the northern half, and 

 especially the northwestern portion, is a real desert. 



This, with the exception of its western part, is the region best 

 known to tourists and visitors, for the reason that the main 

 lines of travel run directly through it from north to south. It 

 presents the same general aspect as the country through which 

 the Southern Pacific Railroad runs from western Texas to Los 

 Angeles. If one passes through it toward the close of the dry 

 season, which extends in its most favorable sections from De- 

 cember to July, and in its most unfavorable ones begins nearly 

 two months earlier, he encounters a region of torrid heat and 



* Abstract of an illustrated lecture delivered to the Torrey Botanical Club, 

 February 14, 191 1. 



[No. 2, Vol. II, of ToRREYA, Comprising pp. 51-76, was issued 21 Mr 1911.] 



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