124 LEAVES. 



a stem, so as to form a leafy border or wing, it is said 

 to be Decurrent, and the Mullein, some of the Thistles 

 and Peas are familiar examples. Fig. 23. 



3. FIGURE. 



With regard to form, leaves are Simple, as in the 

 Lilies and Grasses, or they are Compound, as in the 

 Parsley and Rose. The petiole of the simple leaf 

 terminates in a single expansion, which is either entire 

 or divided, but in the latter case the incisions never ex- 

 tend to the midrib. The footstalks of compound leaves 

 are more frequently subdivided, and the expansions or 

 leaflets in which they terminate, are distinguished like 

 simple leaves by their peculiar form. Of these forms, 

 the following with annexed examples, are more particu- 

 larly important. 



An Orbicular leaf, whose entire margin is in the cir- 

 cumference of a circle is of rare occurrence, and 

 " precise examples are scarcely to be found." When 

 there is but a slight deviation from this form, leaves 

 are said to be Subrotund, or roundish, and the Round 

 leaved Winter green is a good example. 



The Ovate or Egg-shaped leaf, Fig. 28, occurs more 

 frequently, having its base broader than its summit as 

 in the Periwincle and Sage. 



The Obovate is also egg-shaped, but has its summit 

 broader than its base as in the fragrant Clethra. 



The Eliptic or oval leaf, is intermediate between 

 the two preceding, having its two extremities equally 

 broad, as in the Lily of the Valley and Water shield. 

 Fig. 27. 



The term Oblong, is somewhat indefinitely applied to 

 ihose leaves which are several times longer than broad, 



