DISTRIBUTION OP THE VEINS. 153 



exist in the leaves (which is scarcely the case in any but the Ferns,) 

 they are seen to divide and subdivide, each usually bifurcating, 

 or splitting into two branches like the prongs of a fork, at inter- 

 vals ; and in general, these subdivisions do not unite again. 

 Hence, as regards their leaves, the Cryptogamia may be charac- 

 terised as forked-veined. 



230. In the group of Endogens it may be observed, that the 

 veins run in a nearly straight direction, and almost parallel to 

 each other ; and that they have but little connection, by the in- 

 terlacement of their minor subdivisions. The arrangement of 

 these veins, however, differs according to the general form of the 

 leaf. Thus, in the long narrow leaves of the Grasses, and of 

 other Endogens, such as the Lily, Iris, &c., the foot-stalk is not 



FIG. 62. ENDOGENOUS LEAF. 



continued along the leaf as a great central vein or midrib, but 

 divides at once into several veins, which run along side by side, 

 from one e <1 of the leaf to the other ; and as there is very little 

 connection between these different veins, the leaf may be readily 

 .and very straightly torn, from one end to the other. In other 

 cases, however, the leaf is broader, and the parallel veins are sent 

 off from a large central midrib, running in the direction of the 

 breadth of the leaf. As these, too, are but little connected with 

 each other, it is easy to tear one of these expanded leaves into a 

 number of narrow ribands, which will then hang from the 

 midrib ; and something resembling a compound leaf will thus be 

 produced. As each of these ribands will have its own vein 



