DICOTYLEDONE-ffi. 61 



ner as those of palms, only they never rise above a 

 foot or two high. 



Among the Hydrocharldece we find the Vallisrie- 

 ria, the female flower stalk of which is physically 

 curious. Being spirally elastic, it is contracted or 

 dilated according to the depth of the water. The 

 whole plant is submerged ; the male flowers are deci- 

 duous and float on the surface ; at which time the 

 female flower rises to the surface, where a contact 

 takes place. 



SECTION III. DICOTYLEDONE^E. 



WE now enter on the most complicated forms of 

 vegetation, namely shrubs and trees ; and though 

 many, perhaps the greater number, of plants arranged 

 in this class are neither shrubs nor trees, yet as their 

 organisation, and structure of flowers are similar, they 

 are properly placed together : the circumstances of 

 durability and ligneous character not being sufficient 

 generic or specific distinctions in the natural system. 



The chief physical marks of the plants of this 

 class are, that they all rise with two or more coty- 

 ledons or seed leaves, and that they are invariably 

 vascular. As it is only the physical, and not the 

 botanical distinctions which are intended to be noticed 

 in this review, the most conspicuous differences only 

 need be pointed out ; of the former there are com- 



