I. 



INTEOBUCTION 



BY C. C. PARRY, M. D. 



GEOGRAPHICAL DISTRIBUTION. 



Every ol}serving traveller must have noticed how closely the peculiarities of the scenery of a 

 country depend upon its vegetable productions. Not only is this true of trees and the larger 

 forms of plants, but even the humbler^ though apparently insignificant in themselves, have 

 their share in producing the general effect. Hence the subject of the geographical distribution 



may 



the 



Perhaps no region of eq^ual extent presents more marked illustrations of the relation of the 

 vegetation of a country to its topography and geology than those afforded by that lying along 

 the Mexican boundary line. 



The usually difficult task of constructing a phytological map might here be performed with 

 comparative ease, as the observer, little perplexed by a great variety or gradual blending of 

 forms, involuntarily associates particular localities with the predominating and characteristic 

 vegetable productions. Thus one who has ever traversed the desert table lands of the Upper Rio 

 Grande will not fail to unite in his recollection of these tracts the dull foliage of the Creosote 

 bush, the long thorny wands of the Fouquieria^ the palm-like Yucccij and the crimson-flowered 

 and spine-armed Cereus. Still less can any one, who has seen the giant cactus of the Gila in 

 its perfection, ever forget the wild and singular features of the country in which it grows. The 

 distinctness with which the botanical districts are defined gives an unpleasant sameness to the 

 scenery of this country. The extensive plains exhibit a monotonous succession of the same 

 forms, and each mountain slope and ravine presents us a collection of plants quite like those 

 we have so often seen in other and similar localities. Indeed, the botanist in these regions, 

 knowing what to expect in each different situation, soon loses his zeal, and becomes intent upon 

 little else than overcoming space. 



We 



predominat 



into which we have divided it. 



THE LOWER MAKITIME BELT. 



Tlie flora of this strip of country is too well known to require an account here, had we the 

 necessary data for describing its characteristic botanical productions. Its position being 

 intermediate between the ^^ tierra caliente'' of Mexico and the gulf coast of Louisiana, gives to 

 its vegetation a mixed character^ partaking of that of the two extremes. Thus^ while upon the 



2k 



