THE LEAF. 



57 



main rib or ribs branch repeatedly at more or less acute angles, and 

 anastomose by their slender twigs, so as to form a netted or reticular 

 framework ; while in most Monocotyledons the branches passing from the 

 main ribs go off nearly at right angles, become suddenly much more slender, 

 and form a kind of square latticed or cancellate framework when they are 

 strongly developed (fig. 76). 



Forms of Leaves. The general outline of leaves or leaflets is indicated 

 by certain technical terms, such as : circular or orbicular (Hydrocotyle, 

 Tropceolum majus} (fig. 87) ; roundish or subrotund, approaching the fore- 



Fig. 72. 



Fig. 73. 



Fig. 75. 



Fig. 74. 



Fig. 72. An elliptical serrate leaf. 

 Fig. 73. An ovate, acute, and dentate 

 leaf; venation arched. 



Fig. 74. An obovate entire leaf. 



Fig. 75. An entire lanceolate leaf, 



edges revolute. 



going (fig. 71) ; elliptical (fig. 72) ; ovate, egg-shaped with the broad end 

 nearest to the stalk (fig. 73) ; obovate, the same shape, with the narrow 



Fig. 76. 



Fig. 77. 



A hastate leaf. 



A sagittate leaf. 



A cordate and abruptly 

 acuminate leaf. 



