118 



OBJECT LESSONS IN BOTANY. 



often, also, witliout stems. Hence we may say of the Cryp- 

 togams til at they are not only flowerless^ but seedless^ and 

 often leafless and stemless. 



252. We will now dismiss the Cryptogams for the pi-esent, 

 and consider the Flowering Plants (Ph sen ogams), as one sub- 

 kingdom; — how 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 flowers 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 Phsenogamia into 

 two provinces ; as Natui-e has already done. 



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

 pith; 2, 3, two layers of wood; 4, the bark. Fig. 360. Cross-section of an endoge- 

 nous stem (Corn), sliowing no distinction of layers. 



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

 GENS and the Endogens: — two Greek words denoting: outside 

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



254. l^ow, taking such an Exogen as the Apple-tree, and 

 such an Endogen as the Indian Corn, w^e may distinguish 

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

 centric rings, or layers, as seen in Eig. 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 ? 



