9-56 



VEGETABLE 



this class present no articulations with the stems, nor do they 

 fall off, leaving a scar, as in the Dicotyledoncs. Indian 

 corn, and the Grasses are familiar examples, the leaves being 

 permanently fixed to the stalk. The Palm trees all belong 

 to this class. 



DICOTYLEDONOUS PLANTS. Although the name of this 

 class means " two cotyledons," still there are several spe- 

 cies of plants which have four, and a few which have many 

 seed-lobes, as in the case of the Pines. So far as this part 

 is concerned, therefore, this division of the vegetable king- 

 dom is characterized by two or more cotyledons, situated 

 opposite to each other. 



This division is further distinguished from the Monoco- 

 tyledones by the growth and appearance of the bark, which 

 in the latter is blended with the wood, while in the Dicoty- 

 ledones, these parts are separate, and of different vegetable 

 tissues. The wood of this division consists of concentric 

 layers, one of which is annually produced, the whole being 

 penetrated by medullary rays, extending from the pith to 

 the bark. 



Fig. 227. 



Fig. 227, represents the distinguishing Physiological 

 traits of Dicotyledonous vegetables. 



v. A transverse section of a Dicotyledonous stem, show- 

 ing the concentric, annual layers of the wood, and the me- 

 dullary rays. On comparing this with <?, Fig. 225, the 

 difference in the woody structure of the two classes will be 

 seen. 



to. A Dicotyledonous seed, just beginning to germinate. 



x. An embryo with four cotyledons 



