CHAP. I. THE LEAF. 50 



tic flavour for several years even in a dried state, as 

 may be exemplified in the case of Verbena tri- 

 phylla. The leaves of many of the Geraniums are 

 extremely sweet-seen ted, and the odour of the 

 leaves of Mint and Balm is known to almost every 

 body. 



The dietetical uses of vegetables are very often Uses, 

 confined to the leaf, as may be exemplified in Cab- 

 bage, Cellery, and Lettuee, of which the leaves only 

 are used for culinary purposes. The leaves of the 

 Grasses are also the principal food of most quadru- 

 peds ; and there is scarcely a leaf of any plant 

 whatever that is not fed upon by some insect. And 

 so also the medical virtues of plants, as well as the 

 dietetical uses, are found frequently to reside in the 

 leaves, as may be exemplified in the case of Hemlock 

 and Fox-glove, the most potent of simples, but of 

 which the leaves only are used in pharmacy. 



Lastly, as the leaf is only a temporary or decidu- 

 ous part, it dies in the autumn or winter, and is 

 regenerated in the succeeding spring. While it 

 exists, however, it forms one of the principal orna- 

 ments of the plant, and is easily distinguished from 

 the other parts. In the seasons of spring and 

 summer it clothes the plant with verdure, and forms, 

 by its expansion, a cool and inviting shade. And 

 even in its decay and fall it ceases not to gratify the 

 eye, assuming by slow degrees a paler and milder 

 shade, and tinging the forest and the plain with an 

 infinite variety of hues. 



7 



