256 THE GEOGRAPHY 



present on the only ninety-y ears-old Yorullo in Mexico. 

 The bluish Bristle-grass,* which is one of the commonest 

 garden and field weeds on sandy soils with us, grows also 

 in the interior of Brazil on suitable soil. A charac- 

 teristic plant of our sea-shores, and the vicinity of salt- 

 springs, Ruppia maritima, grows equally on the northern 

 coast of Germany, in Brazil, and the East Indies. But it 

 is needless to accumulate examples, for these so hasten to 

 present themselves, that the view finds some support in 

 observation, which assumes that every plant must exist in 

 every part of the globe where the known conditions of its 

 vegetation are present. But on that account have I placed 

 those three scenes at the very commencement of my dis- 

 quisition, so as to draw attention before-hand to the point, 

 that exactly the cases just mentioned, which, at first sight, 

 appear to be natural and necessary consequences of 

 vegetable organization, only occur as rare exceptions thereto. 

 Even the little Daisy exhibits a certain wilfulness. It is 

 wanting all through North America ; and that which we 

 tread down as an insignificant weed in our meadows, is 

 there reared with the most tender care in the Botanical 

 Gardens. If we pass in review the vegetation of different 

 countries, we see that causes appearing similar in our 

 present knowledge of them, bring forth, indeed similar, but 

 by no means the same forms of plants. To the plants of a 

 particular northern latitude correspond in the analogous 

 height of the Alps, situated southward, other species of the 

 same genera, or other genera of the same family ; or the 

 plants of America are represented in the same latitudes in 

 the Old World by plants which are different, but closely 

 allied in their development. Nay, even plants which belong 



* Setaria Glauca. 



