118 



OBJECT LESSONS IN. BOTANY. 



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

 togams that they are not only flowerless, but seedless, and 

 often leafless and stemless. 



252. We will now dismiss the Cryptogams for the present, 

 and consider the Flowering Plants (Phsen 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, whUe 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 Kature has ali^ady 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 barjj. Fig. 860. Cross-section of an endoge- 

 nous stem (Corn), showing no distinction of lay era. 



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

 such 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 



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

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



