16 INTRODUCTION. 





Erose, Gnawed or Jagged (Fig. 63.), irregularly notched 

 or cut. 



Undulated or Waved (Fig. 55.), presenting a waved margin. 

 Fringed or Ciliate (Fig. 64.), bordered with soft hairs. 

 Prickly or Spinous at the margin. (Fig. 65.) 

 Revolute or rolled back at the margin. (Fig. 66, a.) 

 Involute or rolled inwards at the margin. (Fig. 66, b.) 



With respect to surface, leaves present numerous varieties, 

 the principal of which have already been pointed out in speaking 

 of the surface. Thus they may be smooth, hairy, downy, &c. 



Leaves, however, may also be 



Veined (Fig. 67.), when the vessels are more or less promi- 

 nent, and are subdivided so as to form a net-work. 



Ribbed, or Nerved (Fig. 68.), when the 1 vessels extend in 

 undivided lines. 



Wrinkled or Rugose, when the veins are tighter than the 

 substance between them, so that the latter becomes puckered. 



Plaited or Plicate (Fig. 69.), when the leaf is folded, so as 

 to present alternately projecting and retiring angles. 



Curled or Crisp, when the margin is greatly more expanded 

 than the disk, and the leaf thus becomes folded or curled. 



Naked, destitute of all kinds of hairiness. 



With respect to substance, Simple Leaves are 



Membranous, when very thin and easily torn. 



Leathery or Coriaceous, when thin but very tough. 



Fleshy, when more or less thick and juicy. 



Cartilaginous, when more or less thick and tough. 



Flat, opposed to the following : 



Cylindrical or round ; Semi-cylindrical, flat on one side, and 

 round on the other. 



Compressed, when thick and flattened laterally. 



Depressed, flattened vertically. 



Channelled or Canaliculate (Fig. 70.), having a longitudinal 

 groove. 



Keeled or Carinate (Fig. 71.), having a longitudinal promi- 

 nence or ridge on the back. 



Sword-shaped or Ensiform, perpendicular, two-edged, and 

 slightly convex on both surfaces. 



