114 



ELEMENTS OF STRUCTURAL BOTANY. 



As has already been pointed out, the leaves of Mono- 



cotyledonous plants are almost invariably straight- veined. 



170. In addition to the venation, the description of a 



Fig. 145. Fig. 146. 



simple leaf includes particulars concerning : (1) the gen- 

 eral outline, (2) the edge or margin, (3) the point 

 or apex, (4) the base. 



171. Outline. As to outline, it will be convenient tc 

 consider first the forms assumed by leaves without 



Deltoid 



Fig. 147. Fig. 148. 



and whose margins are therefore more or less continuous. 

 Such leaves are of three sorts, viz.: those in wh?ch both 

 ends of the leaf are alike, those in which the apex is 



Figs. 145 to 148. Various forms of foliage-leaves. 



