DESCRIPTIVE BOTANY. 



PART I. 



part of our subject, we shall enter somewhat more fully 

 into the details of a theory, which has been proposed 

 for reducing under general laws, all the modes which are 

 observable in the distribution of foliaceous appendages. 



(83.) Adhesion of Leaves. In some species where 

 the leaves are opposite, we find them " connate," or 

 grafted together by their bases (fig. 73. a), so as 

 completely to surround the stem ; and in other species, 

 where they are alternate, and without a petiole (sessile), 

 the edges at the base of the limb extend round the 

 stem (6), and are united together. Both these 

 cases are termed " perfoliate ; " the stem seeming as it 

 were to penetrate the leaf. In some plants, the middle 

 of the leaf adheres to the 

 stem, through a greater 

 or less extent, whilst its 

 edges are free (fig. 74.). 

 The leaf is here said to 

 be " decurrent," and the 

 stem " winged." 



(84.) Nutritive Organs 

 of Cryptogamic Plants. 

 In art. $6. we have al- 

 ready stated nearly all 

 that it will be necessary for 

 us to mention respecting 

 the organs of cryptogamic 

 plants ; a more particu- 

 lar account would involve 

 us in descriptive details, 

 which belong rather to 

 the department of phytography and systematic botany, 

 with which we do not profess to interfere. The higher 

 tribes of these plants, contained in the division " Duc- 

 tulosae/' have green expansions, much resembling leaves 

 in their general appearance, and like them possessing 

 stomata; but differing from them very considerably in 

 some respects, especially in bearing the fructification 

 upon their surface. These have therefore received a 



