6 The Root. [Book VIII, 



v/mter feafon he covered feveral young trees with var- 

 nifh, leaving the tops of the branches only expofed to 

 the air. They remained in this fituation during die 

 following fummer, when fome of them lived, though 

 in a languid ftate ; but thofe from which the air had 

 been more accurately excluded, died without a fingle 

 exception. To this proof the fame author adds, that 

 trees overgrown with mofs have few leaves, weak 

 ilioots, and fcarcely any fruit; and that it is the com- 

 mon practice of all judicious gardeners to ftrip the 

 mofs from the bark of aged trees, which by admitting 

 the air, generally reflores them to vigour and fruit- 

 fulnefs. 



II. The root, which fixes the plant to the earth, and 

 is the chief fource of its nourifhment, differs much in 

 different fpecies of vegetables. All roots agree in 

 being fibrous at their extremities, and it is by their 

 fibres chiefly that they are fitted to draw nourifhment. 

 The root terminates upwards in the ftem or trunk, 

 Avhich fuftains the other parts of the vegetable. The 

 internal ftructure of the root, or rather of its fibres, 

 differs not very materially in general from that of the 

 ftem. It confifts of a cuticle, bark, wood, and com- 

 monly of a fmall portion of pith ; though there are 

 fome roots which have no pith at all, while there are 

 others which have little or none at the extremities, but 

 a confiderable quantity near the top. The cuticle, in 

 all roots at a certain age, is double; the cortical fub- 

 ilance, or bark, differs greatly in- its quantity and dif- 

 pofition in different plants. In trees it is thin; in car- 

 rots, on the contrary, it is one half of the femi- 

 diameter of the root ; and in dandelion it is nearly 

 twice as thick as the woody part. "1 he roots-, as well 

 as jhe trunk of plants, are furnifhed with a variety of 



veilels 



