DISTRIBUTION OF PLANTS. 11 



special peculiarities in the internal structure ; 

 but in what those peculiarities consist, we are 

 ignorant. 



Some plants , too, are very widely distributed. 

 The daisy, for example, is spread throughout 

 Europe almost universally, in Australia, in 

 Northern Asia, in some parts of Africa, and in 

 South America. In India and North America, 

 however, it is entirely absent, and can only be 

 preserved as a choice exotic, tended with the 

 most zealous care in botanic gardens. The 

 cereals, that is, wheat, barley, oats, rye, etc., 

 are endowed with a very great power of adap- 

 tation. Though their native country is scarcely 

 known, and they are rarely found wild, yet 

 they possess a power of enduring such a variety 

 of temperature, that they have been introduced 

 by cultivation over a large portion of our globe. 

 They can withstand the cold of 62 N. lat., 

 and though they will not in general bear the 

 heat of the tropics, yet even in such places 

 they are sometimes cultivated during the 

 winter season. The potato, again, though only 

 known wild as a native of the western coast of 

 South America, is now cultivated almost uni- 

 versally, particularly in Europe and North 

 America, and has become one of the most im- 

 portant articles of food, especially among the 

 poor. 



On the other hand, many species (and pro- 

 bably the great majority of plants) are very 

 limited in their abodes. The Cactus tribe, so 

 generally cultivated in our green-houses, and so 



