532 CONSERVATIVE ORGANS. [LECT. X. 



the form consonant to the natural habitat of the 

 plant: a, fig. 2, is the natural form of the leaf of 

 Horehound, Ballota nigra ; when it grows on 



dry land; b. h. fig. 3, display the change which 

 takes place when it grows under water. 



Regarding the situation of leaves in relation to 

 the part of the plant on which they are seated, 

 they may be referred to the root, the stem, and 

 the branches, or they are radical, caulinar, and 

 rameal. A radical leaf (folium radicals) is seated 

 upon or springs directly from the root, as exem- 

 plified in the Primrose, Primula vulgaris, the 

 Dandelion, Leontodon taraxacum, &c. ; but ra- 

 dical leaves must not be confounded with seminal 

 leaves, which are the first leaves of the majority 



