LESSON 9.] SIMPLE AND COMPOUND LEAVES. 



61 



LESSON IX. 



MORPHOLOGY OF LEAVES AS FOLIAGE. SIMPLE AND COM- 

 POUND LEAVES, STIPULES, ETC. 



154. IN the foregoing Lesson leaves have been treated of in their 

 simplest form, namely, as consisting of a single blade. But in many 

 cases the leaf is divided into a number of separate blades. That is, 



155. Leaves are either Simple or Compound, They are said to be 



simple, when the blade is all of one piece : they are compound, when 

 the blade consists of two or more separate pieces, borne upon a 

 common leaf-stalk. And between these two kinds every interme- 

 diate gradation is to be met with. This will appear as we proceed 

 to notice the principal 



156. Forms of Leaves as to particular Outline or degree of division. 



In this respect, leaves are said to be 



Entire, when their general outline is completely filled out, so that 

 the margin is an even line, without any teeth or notches ; as in 

 Fig. 83, 84, 100, &c. 



Serrate, or saw-toothed, when the margin only is cut into sharp 

 teeth, like those of a saw, and pointing forwards; as in Fig. 112; 

 also 90, &c. 



112 113 



117 



Dentate, or toothed, when such teeth point outwards, instead 

 of forwards ; as in Fig. 113. 



FIG. 112 - 117. Kinds of margin of leaves. 



