SECT. II. CLIMATE. 431 



the plant from the inclemency of the atmosphere 

 till the return of spring. Trees and shrubs, on the 

 contrary, are naturalized with more difficulty, be- 

 cause they cannot be so easily sheltered from the 

 colds, owing to the greater length of their stem and 

 branches. But nature, always provident for the pre- Or adapt- 

 servation of all her works, and always fertile in sehrs'by" 

 resources for the accomplishment of her object, has nature ' 

 also furnished some plants with the capacity of 

 vegetating in almost all climates, or of naturalizing 

 themselves in almost any. This is particularly the 

 case with greens and eatable roots, such as Cabbages, 

 Carrots, Potatoes, that is, the common culinary 

 plants most useful to man. And hence they have 

 followed man into all climates and quarters of the 

 globe. Some aquatic plants are found capable of 

 vegetating also in almost all climates, perhaps be- 

 cause the water modifies in some measure the tem- 

 perature. Lemna minor has been found through- 

 out almost the whole of Europe, North America, 

 and even Asia;* and Fucus natans, both under the 

 equator and within the polar circles. Plants which 

 grow in the depths of the ocean are not at all af- 

 fected by climate, because they are beyond the 

 reach of the influence of the sun's rays, and air ; 

 go that habitats in this case must be fixed by the 

 greater or less degree of salts held in solution by 

 the water. As the habitats dependant on climate 

 are, like the climates themselves, bounded by certain 

 * Willdenow, p. 395. 



