lis 



OBJECT LESSONS IN BOTANY. 



often, also, without stems. Hence we may say of the Cryp- 

 togams that they are not only fiowerless^ but seedless^ and 

 oftp.n leafless and stemless, 



252. We will now dismiss the Cryptogams for the present 

 and consider the Flowering Plants (Phgen ogams), as one sub 

 kingdom ;^iow shall this be divided? Every one notices a 

 striking difference between plants with parallel-veined leaves 

 and those with net-veined leaves. The former have their 

 flowers three-parted, while the latter have their flow^ers two, 

 four, or five-parted, &c., — the former have seeds one-lobed 

 (monocotyledoned, Less. 15), the latter, two-lobed (dicotyle- 

 doned, Less. 15). Let us, then, divide the Phgenogamia into 

 two provinces ; as Nature has already done. 



Fig. 359. Cross-section of an exogenous stem (Elm), of two years growth: 1. the 

 pith; 2, 8, two layers of wood ; 4, the bark. Fig. 360. Cross-section of an endoge- 

 oous stem (Corn), showing no distinction of layers. 



253. We may call these two provinces severalh^, the Exo- 

 GENS and the Endogens : — two Greek W' ords denoting outside 

 growers, inside-growers, referring to their modes of growth. 



254. Now, taking such an Exogen as the Apple-tree, and 

 snch an Endogen as the Indian Corn, we may distinguish 

 them thus : The Exogen has its wood, if any, arranged in con- 

 centric rings, or layers, as seen in Fig. 360 ; — the outer ring 



252. Show how the Flowering Plants are divided. 253. Please give the 

 character of an Exogen ; an Endogen. Meaning of these two words ? 



